My apartment in Lausanne had a bathroom and a kitchen, except the kitchen was one stovetop and a sink in a small cabinet next to the door. It was small, still cost me 900 CHF/month (in 2006!), but Lausanne is expensive.
I don't think those would be allowed in most (American) cities either, I don't think 20 sqm is rentable.
My first place in London in 2003 was £520 a month, about £875 today. It was a 10 square metre room with a shower in one corner, bed in one corner, small kitchen sink in one corner, and a door in the fourth corner. There was a shared toilet.
Ideally I'd have had a slightly smaller room, but with a private toilet (there was certainly enough space in the footprint for a 2m*1m toilet/sink/shower), but apart form that it was great (given the cost - about half my net income), far better than sharing a house. As a young person needing to be close to a London office but without the luxury of having parents giving me a free room.
I don't think those would be allowed in most (American) cities either, I don't think 20 sqm is rentable.