Well I think the problem is the car isn’t registered until a plate is affixed and it’s likely, from the impact this is having, that consumer law prevents the delivery of an unregistered vehicle.
To my knowledge, there is a similar requirement in the UK for Auto sales, the registration isn’t complete until a plate is affixed. (There was a blip in this process circa early-2018 IIRC, and it led to Fiat having issues fulfilling car sales to their retail partners, don’t recall the specifics but I bought a new Fiat then, and there was some chatter from the forecourt that it was good it was cleared up).