Reflecting from another thread made me realise it was not until my 20s I found out some people expected to have a private bathroom. I went to university then and shared with another mature student who had been married, divorced and said she found having to share a bathroom with unrelated people unpleasant. I had always taken it for granted as had live in jobs and rented bedsits before. She was a lovely person and also the first person I knew who had a glass of wine every evening and she introduced me to many new things - cooking with garlic, sherry, owning and using a car for shopping for example.
So what did you take for granted that surprised other people you met?