What you have to understand about Soviet equipment was that it reflected a different doctrinal outlook and philosophy based on lessons learned on the Eastern Front in WWII.

To that end the Russian concept of operations was that they would use massive amounts of ordnance as a precursor to waves of Armor. They believed that overwhelming numerical strength combined with massive amounts of firepower would help them slowly encircle enemy units and “squeeze” them to death.

So it should come as no surprise that the T-72’s design reflected this strategic plan. The T-64 was well received by the Russians, but they wanted something simpler, that would be easier to train new conscripts on and less complex in terms of mass production. Thus was born the T-72. Like a lot of armies, the Russians sold export versions.

The ones used by the Iraqis in Desert Storm were older models that had been passed down from the Polish Army of the Warsaw Pact era. As such, they were poorly maintained, and had poorly trained and led crews, many of which only had training ammunition. It didn’t help that the Iraqi Army had been badly bloodied in a long war with Iran prior to Desert Storm.

That being said, it’s easy to play Armchair quarterback and say the fight was one-sided in favor of the American M1A1 HA crews, but I doubt many people would be willing to go that moment in time and stand in the TC’s hatch for themselves as the tank crested the berm on that fateful day.

Short answer:

The Soviet Union wasn't "poorly-equipped" in the 1980s. The CIA published this assessment of the T-72 and other Soviet AFVs in 1982 - it gives you an idea of how seriously it was taken by NATO and why the U.S. Army was so adamant about developing better anti-armor weapons.

http://www.foia.cia.gov/sites/default/files/document_conversions/89801/DOC_0000498195.pdf

The Iraqi Army and Republican Guard of 1991 weren't representative of Soviet doctrine, tactics, troop quality, or equipment. Some Iraqi equipment, like the T-72M1s of the Republican Guard, was decent. But even the best-equipped Iraqi units had marginally-weaker equipment than many Soviet units. For obvious reasons, the Soviets were slow to export their best equipment. That meant Iraqi T-72M1s lagged behind the Soviets' latest T-72Bs and T-80Bs. Iraqi tanks had thinner armor, worse optics, and less-effective ammunition than Soviet tanks. Many Iraqi units didn't even have T-72s, and had to use obsolescent T-62s and T-55s.

The Iraqi Republican Guard's Tawakalanah Division and the Iraqi Army's 12th Armores Division were defeated at 73 Easting for many reasons. Part of it was poor tactical deployment too close to a reverse slope that let the Americans get too close. Part of it was bad assumptions about where the Americans would come from. Part of it was technical inferiority.

But the biggest reason the Iraqis lost at 73 Easting was because Americans in 2nd Armored Cavalry Regiment were incredibly well-trained and well-prepared. They made excellent use of speed, surprise, and violence of action to take apart the Iraqis before they could react.

Long Answer:

The Gulf War is certainly an example of American equipment, training, and doctrine working as intended. I don't think the Gulf War gives a very clear picture of Soviet doctrine, tactics, or equipment.

Iraqi doctrine wasn't Soviet doctrine, it was a mishmash of British, Soviet, and homegrown ideas. During the Iran-Iraq War of the 1980s, Iraq had gained and applied operational experience of its own.

Much Iraqi equipment was obsolete by Soviet and Western standards. The Iraqis were still operating large numbers of outdated T-55s and T-62s in 1991.

Iraqi equipment was sometimes comparable to some Soviet weapons. The cream of the Iraqi armed forces, the Republican Guard's armored divisions had T-72M1 tanks and BMP-1 armored personnel carriers they'd imported from the Soviet Union. However, Soviet exports outside the Warsaw Pact tended to be less-advanced (you'll sometimes see Soviet exports derided as "monkey models"). Quite sensibly, the Soviets didn't want to export their latest technology and have it fall into Western hands. Armor historian Steve Zaloga writes:

As a result of the USSR’s export policy, clients such as Iraq did not receive tanks comparable in quality to the best Soviet tanks. In 1990 the best Iraqi version of the T-72 was the T-72M1 – roughly equivalent to the Soviet T-72A, which was already a decade old and not as well armored as the newer T-72B or the preferred T-80B series. Just as importantly, the Soviet Union did not export its best tank ammunition: the Iraqi army relied primarily on second-rate ammunition for its T-72 tank.

This brings us to another issue. The Iraqis' ammunition was a generation behind the Soviets' in 1991. Zaloga again:

…the best Soviet APFSDS around 1990 was the 3VBM-13 Vant, which had a 3BM-32 depleted-uranium penetrator with penetration capability of 560mm at 2km – about double the performance of the 3VBM-3 used by the Iraqis.

Many Iraqi tanks were also old and tired by 1991, as Zaloga notes:

Barrel life was a significant issue for Iraqi tanks as a large proportion of the inventory had been employed during the Iran–Iraq War and the Iraqi army was not especially diligent about keeping its equipment in prime condition; accuracy suffered due to tube erosion.

But here's the thing, very little of this mattered at 73 Easting. Only one American vehicle was hit at 73 Easting: an M3 Bradley from Ghost Troop - it wasn't even hit by a tank, but by 73mm round from a BMP-1 APC. Most Iraqi tanks were destroyed before they ever got a shot off.

This is where we get to the important part: armored warfare is NOT a Top Trumps "Who Has the Best Tank" contest. What happened at 73 Easting had more to do with human factors than it did equipment.

The Iraqis did a great deal right before 73 Easting. Then-Captain H.R. McMaster, commander of 2nd ACR's Eagle Troop later wrote:

The enemy commander, Major Mohammed, and his soldiers knew the ground well. The unit had used the village for billets as they conducted live fire training. Mohammed, who graduated from the Infantry Officer Advanced Course at Fort Benning, Georgia thought it was the ideal ground from which to defend. Unaware of our brand-new global positioning system capabilities, he assumed that we would have to move along roads to avoid becoming lost in the featureless desert. He organized his defense along the road by fortifying the village with anti-aircraft guns to be used in the ground mode, machine guns, and infantry. Mohammed’s defense was fundamentally sound. He took advantage of an imperceptible rise in the terrain that ran perpendicular to the road and directly through the village to organize a reverse slope defense on the east side of that ridge. He anticipated that upon encountering his strong point at the village, we would bypass it either to the north or south. He built two engagement areas or kill sacks on the eastern side of the ridge to the north and the south of the village, emplaced minefields to disrupt forward movement, and dug in approximately forty tanks and sixteen BMPs about one thousand meters from the ridge. His plan was to engage and destroy us piecemeal as we moved over the crest. Hundreds of infantry occupied bunkers and trenches between his armored vehicles. He positioned a reserve of eighteen T-72s and his command post along another subtle ridgeline approximately three thousand meters further east.

Unfortunately, the Iraqi assumption about the Americans using the road was wrong, since the Americans had GPS and could navigate cross-country. The minefields were ineffective at stopping the Americans and did little serious damage. The Iraqis' reverse slope defense was too close to the ridge, so they didn't have much time to react when the Americans crested the ridge.

73 Easting is more an American victory than an Iraqi defeat. It was a soldier's victory. 2nd Armored Cavalry Regiment (2nd ACR) was an extraordinarily well-prepared unit. They'd drilled intensively in Germany. They'd drilled intensively in the Gulf. They were highly-motivated, well-lead, and extremely self-confident. Yes, 2nd ACR had the cutting-edge Bradley and Abrams. But they were successful at 73 Easting because they were prepared to make the most of their equipment and not simply because they had great tanks.

When 2nd ACR made contact with the Tawakalnah Division, they reacted faster than the Iraqis could respond. Speed, surprise, and violence if action are critical ingredients of modern warfare and the 2nd ACR made the most of all three.

https://m.youtube.com/watch?v=jsS9oLAoW8g - A conversation with 2nd ACR's 73 Easting veterans. Note the discussion about 2nd ACR's intense training and preparation. Well worth a watch!

Before I end, I wanna plug Ken Pollack's excellent book Arabs at War. We often get the American perspective on the Gulf War, but Pollack does an excellent job showing the Iraqi side of things. He makes a good point about the limited Iraqi successes you don't always hear about:

The Tawakalnah fought measurably better than its counterparts in the regular army, although it still performed far below Western standards. In particular, its men destroyed and damaged more U.S. M-2 and M-3 infantry try fighting vehicles than any other Iraqi division and actually put out of action four U.S. tanks a feat no other Iraqi unit was able to accomplish.