So it seems all my imagined reasons are correct! I only have one sink here, but if I used a plastic bowl, I'd have to store the thing in a very small kitchen; besides I usually only have to hand-wash pots and I put the water directly in them.

Surely all your sinks are metal? I've never seen anything else.

We use woven cloths too, though I prefer microfibre, and there are also very thin, flexible sponges which are basically cloths; these are used a lot but I never liked them as they don't seem as hygienic. Cloths dry out better.

I can't imagine using towels for more than one purpose! We don't share bath towels either, though I had one English friend who said her family just used any dry towel to hand.