In defense of the Soviet Union, these zoning laws don't come from there. They come from the US, as an effort in the early 20th century to keep undesirable people (jews, blacks, chinese, etc.) away from precious whites.

True, and I didn't mean to imply that Euclidean zoning was invented by the Soviets. Rather, the Soviets, having a planned economy and authoritarian system, planned urban development: they decided how housing would be built, where, and what type. Their choice gave them big apartment blocks, but it was because the State mandated this, not because any developers or private landowners wanted them.

In the US and Canada, it's very similar, though a bit different: the State has decided that only ridiculously inefficient single-family housing is allowed to be built.

Both of them are situations where the State has forced limits on what kind of housing is allowed, but the type of housing is obviously diametrically different. A better system is one where the State sets very few limits on housing, only very practical ones (no 50-story towers next to the airport, for instance), and lets landowners do what they want with their land, within reason.

That is an epic level of reach.

The Soviet union mandated single family housing?

The Soviet Union mandated certain types of housing, so yes, the situation is nearly the same.

The Soviet Union preferred to build a certain type of housing: Cheap and high density. The situation is almost the exact opposite.

No, it's not the exact opposite at all. You're being intentionally obtuse or intellectually dishonest. My point is clear.