Even worse, all carriers have to do is not allow devices on their networks without their logos. I know Sprint used to do this -- unless the phone had a Sprint logo on it, it would not get activated by them.
SIM cards are nice in this respect. Cellular providers *could* go by device IMEI and ban stuff, but that is usually too much work.
I have had enough of lock-in, where I have to change my device if I want to move carriers, or use another in a country. SIM cards are not that bad, compared to the alternative of pleading with providers to allow them to put your phone on their networks.
SIM cards are nice in this respect. Cellular providers *could* go by device IMEI and ban stuff, but that is usually too much work.
I have had enough of lock-in, where I have to change my device if I want to move carriers, or use another in a country. SIM cards are not that bad, compared to the alternative of pleading with providers to allow them to put your phone on their networks.