It's likely the other way around: most Soviet block cities have not only historic centers equally centered around walking/biking but Soviet city design focused strongly on public transport and walkable neighborhoods because cars were unaffordable to most people.

My experience in ex-Soviet bloc countries is the opposite. Unmaintained sidewalks, parked cars blocking safe walking access, unsafe driving behavior/routing near pedestrians.

I often think of a time in Sofia, Bulgaria where I saw an elderly woman trying to get around a car parked on the sidewalk, up against a wall, by walking on the car bumper with her groceries. It was terrifying and precarious.

yeah, my experience is mostly limited to Poland and Czechia. But I would say that issues around the maintenance of public infrastructure apply to more than just sidewalks. And the attitude of drivers towards pedestrians/cyclists isn't great in most European countries (outside of the Netherlands)

In the US, I'd bet the rich half rides bikes more than the other half but the other half commutes by bike more than the rich half. That likely depends on location, though.

only for recreation, not for getting around... at least that is my anecdotal experience.