We don’t have a proper ID system. Or more importantly the national database of who everyone is, where they live and whether they have the legal right to live here. It’s basically a bit of mess, because the idea of a real ID system has always been opposed as not a proper British thing to do. Largely scaremongering that the police will stop you on the street and say “papers please”, which doesn’t need to be part of it at all.
It shouldn’t require you to have a smart phone, it shouldn’t mean that you have to produce it any given time. Hopefully it won’t. But I’m not opposed to ending the current nonsense of proving your identity by fishing out a bunch of bank statements and utility bills.
I expect the right to be up in arms about it, even as they whinge about immigration in a system that doesn’t even really keep track of who’s in the country.