In my experience when the terminal is 'broken' I say "ah shucks I don't have any cash" and they turn back to the terminal which is suddenly working again and, perhaps begrudgingly, accept my contactless payment. I live in a big city and routinely visit a restaurant that does this every time. You'd think they would recognize a regular and quit with the bullshit but nope.

This is exactly my experience every time. My wife is always annoyed at me when we eat out and I insist on using a card, but it's too amusing for me to watch the entire staff struggle around - as if a client with a credit card is some crazy situation they've never encountered before in the center of Munich.

Which is why many places actually assert that they don't take cards before taking any requests.

At least it is common in NRW to do so.