Am I right in thinking that proxy wars have become more common than they have been in the past? If so, what is motivating countries to avoid direct engagement with each other?
I was thinking about the situation in Yemen specifically; one of the explicit goals of Saudi Arabia's campaign there is to ward off Iranian influence, but why not just attack Iran directly, or take over Yemen instead of installing a more friendly government?
This seems more relevant for AskHistorians than AskPolitics though, since it seems like a historical trend. I can think of the Great War of Africa as another example. So yeah, why have countries not faced with devastating consequences (like an American/Soviet nuclear war) decided to not just go toe to toe with each other directly?
I have to say I do not agree with the claim that they have become more common. Primarily because your time frame of the last 100 years contains the 2 largest, most deadly conflicts in human history, which in no way could be considered anything but direct confrontation.
In addition you have a long history of Proxy wars before 1900, from the US backing Texas against Mexico, the British and French in India, the numerous colonial wars between settlers of different nations and allied Indian tribes. So long as there have been spheres of influence there have been proxy wars.