T-72B3 are actually a capable tank. Modernized version like B3M could be at least on par with M1A1. It's not strange that it can take M1A1 out if facing each other.
Tank nerd look down on T-72B3 a bit too much, it's not the best in anything but it serve it purpose as cheap and capable tank.
You're confused here.
2A46 which is the 125mm gun designed for T-64, and used by T-72, T-80 and T-90 is capable of firing modern ammunition - e.g. Svinets, Vacuum APFSDS rounds - that can plausibly penetrate M1A2 armor at 1000-1500m provided that the T-72B3 variant is modified to use it which requires upgrades to the autoloader etc. Not every T-72B3 batch has been upgraded to use modern ammunition but if they are the gun will do its job unless it's already been used too much and has deformed - which is a problem for longer barrels like those used in Soviet tanks or the L55 in Leopard 2A6.
T-72B3 is a
piece of junk with horrible ergonomics, mobility, reliability and poor gun stabilisation that is rightfully looked down on by anyone who has any idea about tank operation, let alone having the questionable pleasure of ever riding in one. The only reason why I am referring to it as a
piece of junk is because a
stronger term is reserved for T-55A - both tanks having served in the Polish Ground Forces well into the 1990s.
However in a tactical scenario it is perfectly plausible for an M1A1 or even M1A2 (the important difference here is commander's independent panoramic sight in M1A2) to place itself directly in the line of fire from said
piece of junk because the crew of the M1 is inexperienced, the operation was poorly prepared, recon was not properly conducted or just because of plain bad luck. Once M1 is in the line of fire of a
piece of junk which can use modern ammunition the chances of getting destroyed are non-trivial, especially if the crew has acquired some practical skill in operating their tank.
But that's because almost everything about tank operations is about not getting in line of fire of another tank. That is actually what makes a tank either a good tank or a piece of junk. On equal terms, in a situation that is described in Polish as "bój spotkaniowy" (lit: encounter combat) that is a situation where tanks of both sides enter the battlefield and have to seek out the enemy, you really don't want to be in a T-72B3 when facing against a technically superior tank, especially a western 3gen like Leopard 2 or M1A1. When Poland made its PT-91 in the 1990s the intended tactic was to use masked defensive positions against the enemy. And the enemy was obviously Russia, so PT-91s would go against T-72s or T-80s. It was acknowledged that PT-91 was not mobile enough to reliably maneuver in spontaneous combat. That approach was changed when Leopard 2 was adopted in 2003 because Leopards are
mobile. But it required training of
professional crews and commanders which is not something that Ukraine is capable of apparently, hence the regular misuse of western equipment. It's very much like having a cossack who has learnt to fight with a saber and giving him a rapier. It won't work. Even if you explain how to use the rapier the habits will take over during combat and that will end badly if the opponent is a competent fighter.
Also an interesting observation: the Ukrainian T-64B is a slightly better
tank compared to T-72B but the upgrades that Russians have done in the 2010s put modern systems in greater number of T-72Bs compared to what the Ukrainians did with their T-64Bs. The T-80 and T-90M are the better tanks. compared to T-64B and T-72B3 is just junk that is available in large numbers.
Russia doesn't really have good
tanks. It has
poor tanks that are
well protected and
well armed, and some of them have
decent sensors and communication systems but their reliability and mobility is awful. Even the turbine-powered T-80s. And that's something that Russian tacticians are very well aware of because they apply tank tactics that reflect the strengths and weaknesses of their vehicles very consciously. This is for example why Russia still uses 3-tank platoons instead of the superior 4-tank platoon. There's no point in using a 4-tank platoon if you can't reliably use tank mobility, because what 4-tank platoons offer is tactical flexibility where two pairs of tanks coordinate by maneuver. Russian tanks fight either with full platoon or as a single tank in firing position rotating within the platoon. It's not that Russian tankers can't come up with better tactics. It's that Russian automotive industry can't deliver a transmission and steering system that would allow the tank to move forward and reverse with at least 25km'h cross-terrain. This is why the 30-tank battalion and 10-tank company is useful. It's the crude middle ground between having a somewhat capable tank battalion for tank regiments and having a poor quality mass tank for infantry support in motor rifle regiments.
Really, a good tank is all about chassis (mobility) and crew (ergonomics). This is why Leopard 1 performed much better compared to T-55 despite being a tin can. And that's something that Poland has also been able to test in practice.
Oh, one more thing. This is why the Swedish Strv103 actually was a pretty good tank despite poor armament (105mm) and insufficient armour. It was extremely mobile and from what I heard from people who used it or were able to see it in action it could run proverbial circles around T-80s and would win on initiative even though it had no turret and had to stop to fire. This is how mobility matters in tank warfare. When you don't have mobility you're much closer to a bunker with a gun. This was why NATO and Warsaw Pact had such mismatch in tank numbers. Western automotive industry was very capable so it could deliver good quality mobility components with good reliability. Soviet automotive industry was not capable, so tank factories made greater numbers of tanks to balance lower mobility and reliability. USSR wouldn't have made so many tanks if it could make tanks of comparable quality in mechanical terms. And again, this was a conscious decision, because it was something that every tanker in Polish ground forces was taught as part of training since 1970s. WarPact had more tanks to throw them everewhere at once and keep going because NATO had more mobile tanks that could maneuver better in defense. There were more basic tactical considerations like these but that's one that is very important, very central, and regularly ignored by pro-Russian keyboard warriors who try to pretend as if Soviets weren't rational military planners, because online keyboard warfare is all about the ego of the keyboard warrior, and not about actual success in actual warfare.
Anyway, that's all. Hopefully you learnt something from this.