One problem no one has mentioned, is that it also makes life a lot harder for homeless people. I guess they need to open a bank account and start writing their account number on a cardboard.

This actually reminds me of when I went to a restaurant a while ago. I had some physical money to spend, so I figured I'd take it with me and pay with that. At the end of the meal, while my friends paid with a card, I asked if I could pay with cash. Immediately, the waiter's demeanor changed and he looked almost... disgusted? I don't even know. Then he asked me in a tone that matched his expression if I didn't have a card, and I answered something like "Well, I do, but it would be more convenient for me to pay with cash, if that's okay". Then he, for some reason, repeated the question, and I answered similarly. He didn't say anything and just avoided looking at me. While a friend next to me was paying I asked again, "so, can I pay with cash?", and without looking at me, he just barely shook his head yes. So I paid with cash, and then I awaited my 3€ change back (in my country it's not usually custom to tip because waiters actually get paid full salaries). Eventually he came back with our receipt, but no change. I just left without saying anything - at this point I wasn't going to argue about 3€ - but I'm most definitely not coming back to that place.

Still don't know what the dude's problem was, but it did leave me wondering how are homeless people expected to pay for anything, if even a person who isn't homeless can receive such cold treatment just for choosing to pay with cash.