What do you mean without a centralised id system? Whose id are you going to carry then? How many entities will you end up with issuing them? How many types will an arbitrary place that needs to check your id accept?
This is such an odd comment given that this is literally how the US has always and still does work, and also how passports will continue to work.
You can present your out-of-state id, birth certificate, license plates and have them accepted anywhere. Universal != centralized, we build systems like this every day -- DNS, TLS, GPG, hell UUIDs.
They're not really decentralised - more delegated, right? Can any state decide to not allow another state's driving licence? What about birth certificate? They're documents valid/expected at federal level.
You can present your out-of-state id, birth certificate, license plates and have them accepted anywhere. Universal != centralized, we build systems like this every day -- DNS, TLS, GPG, hell UUIDs.