[themafia]

> driving is a privilege

Yet you can have a license without owning a car. They don't issue you a plate to use. So the plate is clearly for something else, mainly I think, to indicate that you've paid the appropriate registration fees on the vehicle. The plates are tied to a vehicle to prevent the obvious "plate swapping" attack that people would use against this regime.

> roof that you've paid a bit for the infrastructure

Actually those are gas and sales taxes, are they not?

> you're required to wear the wrist band.

The wrist band need not have a unique identifier readable from several feet away emblazoned on it in order to function.

[freedomben]

> So the plate is clearly for something else, mainly I think, to indicate that you've paid the appropriate registration fees on the vehicle.

I think it's so they can identify the car owner quickly and easily and hold them liable for any law violations or damage. And of courese, at least partially (or ostensibly) for revenue generation and taxation purposes (though if that's all it was for, just using the VIN would make more sense IMHO, which is why I suspect it's more for the former).