[cesarb]

I can think of a single advantage: one less thing to carry. In the extreme, all you'd need to carry would be your smartphone/PDA; everything including your identity card would be in it.

We here are all technical people, and can easily see the myriad ways in which this can fail (starting with: what happens if your phone battery does not have enough charge), but if you ignore all these many disadvantages, one can sort of see an utopic ideal behind it.

(In real life, I've seen people do the "all you need to carry is your smartphone" trick by using phone cases: some phone cases have small pockets, in which one can stuff an identity card, a bank card, and a single key without the ring, without getting it too bulky.)

[CogitoCogito]

> I can think of a single advantage: one less thing to carry.

This system _adds_ the requirement of carrying a smartphone. This is one _more_ thing to carry not one fewer.

> if you ignore all these many disadvantages, one can sort of see an utopic ideal behind it.

Yes it is true that if you ignore all the problems in a system, then the system has no perceived problems.