Requiring identification was a very touchy subject in some European countries for a long time because the Germans implemented just this requirement in '40-'45 (called an 'ausweiss'). Not complying was an offence that could result in deportation or even death. It was also meant to aid in rounding up Jews and other groups.

In some countries idenitficaiton requirements (especially if it is blanket) still stokes a bitter discussion as there are enough people left who remember.