Features like this really do require a subscription model. This isn’t enabling remote start by pressing a key on your fob. This is sending a request to a server, which connects to a cell tower to broadcast signal saying “turn on this car”. That stuff ain’t free. Someone has to pay AT&T for the data connection.
Only because they unethically intentionally designed it that way, when they could’ve just as easily picked a different design that could’ve worked entirely locally. They are inventing excuses for rentiership.