Nobody would put up with buying a car that only runs off gas from ExxonMobil, even with a discount. Nobody would buy a laptop that can only get an internet connection through Comcast. That so many people put up with locked phones are OK with this practice shows a lack of comparative analysis.
I’m of that particular age where my memories start just after AT&T was broken up into Baby Bells (to the extent that I thought “Ma Bell” was a weird shortening of Mountain Bell). So I know we’ve been here before.
Tesla’s not a great example, given that their connector is now a standard. Yes, it’ll take year for other charging networks to get built out, but that’s a temporary situation that’s a tech question. Cell service is not.