Depends on what you mean by "Intervened."

If you look at places like Western Europe, I would argue that reconstruction has been just as successful in those places as they were in Japan or Korea.

If you mean "Intervened" as a nice way of saying "fought against", well, it's simple: Japan and Korea were able to take advantage of the unique opportunities they had.

After Japan ended its isolationist period, it industrialized and modernized at an almost unbelievable rate. The Perry expedition to Japan landed in Edo bay in 1853. Japan defeated Russia in the Russo-Japanese war in 1905. That means in only 50 years, it became a great world power in its own right. Sure, in WWII, Japan couldn't hope to compete against U.S. industrially or militarily, but the Empire was still very much a force to be reckoned with. Japan was very industrialized, had a modern, efficient, education system, and had a functioning government based on meritocracy. Although the war was devastating for Japan, the strong foundations for a prosperous nation was very much present. Coupled with an almost completely homogenous population, it was a country that still held massive potential for success.

But potential means nothing if there's nowhere for that potential to go. Fortunately, the U.S. got itself into another conflict just over the pond: Korea. The U.S. occupying forces needed resources and a skilled workforce as close to the action in Korea as possible. As a recently subdued country that was right next door, Japan served as the perfect base of operations for a war in Korea. So when the U.S. spent money in Japan as both a part of the Marshall Plan and for the acquisition of necessary war material, it helped boost the local economy and ease Japan out of post-war ruin. Furthermore, since Japan became a de facto "protectorate" of the U.S. after the war, by close ties to the U.S., it enjoyed top-flight access in exports to the global market through its link to the U.S.

Korea is very similar. Obviously, it has to whether another decade of instability and war unlike Japan, but in the grand scheme of things, it was still very similar. Korea, although obviously not as developed as Japan proper, was still a part of the Empire before its dismantling, and therefore, had been developed by the Japanese occupation in terms of infrastructure and government structure. So everything that has been said about Japan pretty much applies here. Japanese and Korean companies also had close connections due to the fact that they were once under the same government, and therefore, Korea also enjoyed access to the global market both directly through the U.S. and through its connection to Japan.

So with both Korea and Japan being relatively stable (although, as my family will tell you, Korea did enjoy its fair share of coups and counter-coups), they would have inevitable slowly climbed out of their ruined states and ended up as decently developed nations. However, the electronics revolution changed all that. Because Japan and Korea had a very good, educated populace, they were able to seize the Electronics market in their bids for Export-Oriented Industrialization and make a fortune in the newly emerging computer sector. Furthermore, both countries were able to embrace very rigid quality control methods while this was happening, meaning that East Asian products were sought after by international consumers as higher quality, and more often than not, more affordable alternatives to their "western" manufactured counterparts. This obviously means that Japanese and Koreans goods were in high demand, and both countries experienced a massive economic surge, that thanks to the aforementioned stable, responsive governments, they were able to use to further develop the countries.

This is, very obviously, different from let's say, the middle east. The middle east was ruled for a very long period of time by the Ottoman Empire, which failed to embrace industrialization, which meant that these regions were economically underdeveloped. Furthermore, without the presence of a strong, centralized education during the interwar era, they could not go the route of East Asia in industrialization. This, punctuated by a series of very bloody conflicts resulting from a very diverse population, meant that the region faced, and still faces, many more challenges if it wishes to reach the level of prosperity enjoyed by Japan and Korea.

In Latin America, the challenge comes from the fact that the region has a very long history of corruption and mismanagement that hinders the region's true potential. This, along with exploitation by U.S. and European companies in the 19th century, means that it was very difficult for them to pursue solutions that could have potentially brought them out of poverty.

In short, Korea and Japan had several key assets that allowed it to prosper post WWII, while the other regions that America intervened in did not.

**Edit: Grammar fixes

I am just an undergrad Year 2 History student, so take my answer with a pinch of salt since I believe I lack the Academic prowess of other members of this forum. Also, apologies for the lack of sources, I'll endeavour to find some but most of this information comes from compressed notes and readings provided for my institution and prof, which I am unaware has an exact text or online form which I can link or cite here. Nevertheless I believe they are accurate, but due to this I shall refrain from giving specific figures out of fear of inaccuracies.

To expand a bit on your question prior to answering it. America primarily "intervened" in Western Europe and the Far East to aid in the reconstruction. I assume what you mean by intervention is the provision of economic aid and some an extent an American Presence in the country. And I would assume that this falls under more of economic history given how it focuses on reconstruction.

I am unsure of what comparison your making in particular, since both Western Europe as well as ROK and Japan both had wildly successful postwar economic booms thanks to the US. The Marshall Plan in the Europe helped economies there boom through what was essential large grants of money to the Western European countries. No where else was the US as heavily involved as reconstruction other then these two regions. Hence if the comparison is to countries in other areas the simple answer is that the US did not focus anywhere near as much effort there, hence less spectacular results.

Honestly, the success of both Western Europe's Economic reconstruction and Japan's had similar causes. As for the ROK it is slightly more complex due to the Korean War but in general it has the same few characteristic.

Firstly, it is the presence of US Aid. For Western Europe that was the Marshall Plan. For Japan it was the treaty of San Francisco that struck off the war reparations Japan needed to pay as well as investment from US firms into Japan through the 1950s and 1960s. Large Japanese cooperations know as Zaibatsus were allowed to reform despite being broken up by the occupation government as they were seen as being instruments for the Japanese War machine they were trying to dismantle. This helped to jump start their economy despite the war leaving it in ruins. Similarly, the ROK benefitted from this after the Korean War as there was a large influx of US aid and investment.

Next is the presence of US troops. Western European countries eventually benefitted from NATO and West Germany in particular hosted US forward based forces. This does help on the micro level of them spending money but in the big picture it means defence spending can be reduced given the strong US presence. The same can be said for Japan which wasn't allowed to have an armed forces for quite some time and relied on the US to defend them. This basically meant that during the Cold War where defence spending was going through the roof Japan didn't have to spend a single cent on it allowing them to use that money for the economy helping with their growth. Similarly South Korea also has US forward garrisons helping to alleviate some of their defense spending, although this did not have a very big impact given their leeve en masse policy.

That point may sound counter intuitive to thinking we are familiar with, but all the realpolitik aside, that was the political climate of the world at that time. They had just existed a World War, no country wanted to continue military spending (besides the USA and USSR due to political considerations) and they were seeking a climate of stability where they had dependable allies. So while it does seem ill-advised to reduce military spending and rely on forces of another country to defend you in the event of an attack that was the thinking at the time. And the US wanted to make it self known as a reliable ally in the context of the Cold War where more allies mean more prestige for them and less for the Soviets. Of course this only really persisted from the late 40s to the 1950s. Once the cold war escalated and even during detente spending was back up for a majority of countries. However this brief period immediately after WWII of reduced military spending helped towards their successful reconstruction.

Lastly, I would also like to add that the US is not entirely responsible for reconstruction being a success. Local governments in both the Far East and Western Europe played large roles. The Europeans developed the European Economic Community and adopted their own mixed economy plans. The Japanese had a large climate of political stability due to the "Iron Triangle" and geared themselves to becoming a heavily export focused economy. South Korea also similarly adopted a mixed economy and gear themselves to be export focused. This all contributed to their successful reconstruction. It's difficult to say which was more important since US aid was essential, but it was also the aid being used effectively by the recipient countries that created the economic miracles after the war.

If your interested, I recommend further reading on the Japanese Economic Miracle for a more detailed explanation. If your interested in the general reconstruction after WWII you could also read up on the Marshall Plan and the Bretton Woods System which created the environment for the Golden Age of Captilaism, a title that has been assigned to the early post war era due to high sustained economic growth.

This is a great question, and it's something I have studied quite a bit. Japan and Germany are usually looked at as some of America's most successful foreign interventions, contrasting directly with other efforts such as the Iraq situation.

One thing to keep in mind, though, is that your comparison is a bit overly broad. Japan and Korea are VERY different situations. Japan was a country we defeated in war, a country that had an unconditional surrender, and a country that we "rebuilt" after the damage we helped cause. Korea we never conquered, their government never surrendered to us, and we did not have to rebuild the country from a ground level. They are not really fair to compare because they are not at all similar situations.

Japan is similar to situations like Germany and Iraq--countries we have gone to war with, defeated the existing government, and had to rebuild up from the ground because all economic, industrial, and social systems are broken. America has largely NOT engaged in this kind of situation, though it has a decent track record when it has, its sole failure being Iraq.

Iraq failed for a few reasons, but mostly because the occupying forces failed to create a more stable economy and social structure, instead making it worse. By disbanding the military and ending employment for anyone connected to the state run Ba'ath party, the US forces managed to make a bad situation worse and remove the few jobs still available. Coupled with an insufficient military presence and a failure to focus on getting economic and social structures running before spreading democracy, a promising opportunity turned into and insurgency.

In Japan and Germany, this policy was very different. Only the highest level Nazis were disbarred, with all the low-level party officials (such as school teachers and basic beauracrats) still keeping their jobs. The focus was on getting food on tables and jobs in the economy, not in spreading American freedom. And the manpower was there to make sure it happened decades into the rebuild. It worked much better.

As for Korea, that doesn't really have a parallel. They were somewhere between and alliance and an intervention. We didn't really replace the government of choice with someone we wanted instead as we did in the Americas. We just propped up a rebel faction that already had a strong base of popular support and a weak opponent. But it also wasn't exactly a full alliance with a real government as the South Korean rebels weren't really established yet and didn't have much military power without us providing the muscle.

The real reason for success in South Korea came from the weakness of the opponent. We never lost the hearts and minds like we did in Vietnam because our guy in Korea had actual popular support unlike our guy in Vietnam. Coupling that with the North Koreans having a largely ineffective regime, it's not hard to see why US intervention worked there. This is very different from Latin American interventions where we just picked a "strongman" and made him the new government whether he had support or not.

Some great books to explore this topic further are Inside the Emerald City by Ray Chandrasekaran and The Warrior and the Priest by John Cooper. The first is a comparison of the Iraq occupation to Germany and Japan from the perspective of a journalist living in occupied Iraq. The second is a contrast of Teddy Roosevelt and Woodrow Wilson and their different approaches to nation building.