Whenever I check into a hotel in Spain, they ask me for ID. A credit card and loyalty card for the hotel chain doesn't seem to be enough, it seems to need to be some sort of official ID.
It seems that the expectation on the part of the staff is that you'd hand over your Spanish ID card, or failing that an ID card from another EU country. Since I come from a country that doesn't have ID cards, I don't have one like that to offer. Instead, I've tended to hand over a photo driving license, in part because it's in my wallet with my credit cards. Some hotels seem fine with this, some say it's OK but get very confused filling out their guest form with it, some seem very unhappy. Almost none seem to think to ask for a passport, they all explicitly seem to ask for ID.
My question is therefore in two parts. Firstly, is this checking of ID a legal requirements in Spain, or is it just something the hotels seem to like doing? And if it is a legal requirement, what is and isn't acceptable ID to offer to the hotel?