Another possible problem that I came across yesterday at work in Britain - we have card reading machines that can handle chip and pin, chip and signature, or swipe and signature. However the number of swipe and signature cards we see is vanishingly small and on trying the first one for months, we found the swipe facility on the machine had stopped working. Yes, we know how to use it correctly, and the machine has been handling chipped cards happily before and since.
We have manual backup - the original handwritten sales slip and imprint system, and we can obviously explain what's happening in English to visitors from North America. But elsewhere in Europe problems with dirty magstripe reading heads or slots full of fluff might cause greater difficulties to tourists.