What's the purpose of a signature even? The retailer is not allowed to (by terms of service) ask you for any ID to compare it against. This is just trappings for show.
So there is some regional variation in practices.
Anyway, this mostly faded away since most of new cards are chip&pin and, more importantly, in Italy most of the people use debit cards (Bancomat is the common debit circuit here) or... cash :-\
Of course, no one checks these days.