@Eamonn ******
the simple answer is convenience, I am involved in the service industry and the amount of people who lose their cards or have problems that take days to a week to sort out (3 weeks to get a new card) is large.
I like that if this happens I can go to a local bank without international phone calls, fix it in an hour and then go and use the card to buy things as required without having to plan an arm visit first. Mind you I live here, if I was a tourist I wouldn't bother