For the sake of reducing complexity in an already very complex world, I'd rather that it be illegal to require an email address to sign up for an account (or, alternatively, make it illegal to require an account for things like making a reservation at a restaurant) then being provided with an email by the USPS.
Doubly so given the interactions that I've had with digital services provided by my country's government and the bad (and in several cases extremely bad) experiences that I've had with them.
To be clear - I don't object to e.g. an address from the USPS complementing my existing email - I just don't want to be forced to use it for anything due to it being given some special properties that normal email providers aren't.