The Soviets built tanks according to their philosophy - attack! attack! attack! and “There is a certain quality to be found in quantity.”
The Soviets also had huge areas, east and west, to defend (or attack). They had to have lots of tanks and they had to be highly mobile. That’s why they’re such lightweights.
Yes, the Soviet economy sucked (i.e. standing in line for lousy bread and crummy shoes) so they couldn’t afford all all the bells and lights and gizmos we mounted on our tanks. And their QA sucked, too.
But the darn things are ubiquitous. They’re all over the place and they seem to last forever.
They last until they meet a depleted uranium round or a Hellfire missile. Yes, “Quantity has a certain quality all it’s own’’ but with the Russians the former never matched the later.