Anecdotally, I think you're generally right that Europe isn't as heavily into plastic (whether credit cards or something else) as the US. (Though they're pretty widely-accepted in the UK where I spend most of my European time.) I'll be in Germany at the end of the month and it sounds as if I should definitely expect to pay cash a lot of the time.

Sweden does seem to be this cashless outlier for some reason. [EDIT: I gather it's a Nordics thing more generally.] I think it was also featured in a Freakonomics episode fairly recently.