They don't just teleport into a stack in the parking lot of the post office on their own. A pickup would involve employees. Who are members of the union.
As I understand it: The law is that the government agency must make new license plates “available” to Tesla. They tried to argue in court that it was sufficient for them to put license plates in the mail. But the court sided with Tesla, at least in the interim. So it’s definitely not open-and-shut case for the unions.
They don't just teleport into a stack in the parking lot of the post office on their own. A pickup would involve employees. Who are members of the union.