They may have existed somewhere, but I'm not aware of any in my home town.

As with many things in the USSR, it may well have been regional and time-dependent. My memories are from mid-80s, although I know that my family had one before then. I didn't know anyone whose family didn't have one, and we weren't a nomenklatura family or anything like that - just a regular Soviet family with boring everyday jobs (teachers and engineers) - and neither were our neighbors and acquaintances.

When I've lived in hotels longer than a week at a time, I've sent just collared shirts and slacks to the laundry. Everything else can be satisfactorily washed in the bathtub. One place I stayed in Tokyo had this really long shoehorn in every room, which was ideal for stirring the tub.

Yeah, plenty of people in Poland would just wash their clothes either by hand or with a really cheap washer. And dryers were rare and land was plentiful, you'd just air dry.

Not that people don't own them now, but what they own now is a straight-up upgrade from what they had before.

At this point I'm sure there will soon be a market for laundromats in Poland, at least in the more urban areas. But it'd be a hard sell for the vast majority of Polish folks.