That's only true for Schengen (which is a limited selection) and doesn't cover you having to show ID or passport to customs or simple random checks. This merel

That's only true for Schengen (which is a limited selection) and doesn't cover you having to show ID or passport to customs or simple random checks. This merely covers having to show your ID or passport for crossing the border, you're still beholden to the laws of the country you enter.