It is already a thing, just not prevalent. Although I believe for the moment, you still have to choose your radio-specific variant as the transition to 4G and 5

It is already a thing, just not prevalent. Although I believe for the moment, you still have to choose your radio-specific variant as the transition to 4G and 5G isn't 100% complete yet; CDMA vs GSM. (I hope I'm wrong about this by now). Sometimes it's (or was) based on spectrum. Another issue is probably the "incentives" provided through the network providers and their partners, especially when an iPhone is traded in. Often times it results in significant "savings" for the consumer. (I imagine Apple could implement something similar, if not superior if they wanted) Finally it's physical presence. Apple has done a fantastic job of creating a physical place to serve your needs, and of course you can always buy online, but there are those that prefer or require going to a place to take care of their phone needs. I also shudder to imagine what the Apple stores would look like if they had to deal with and resolve the kinds of network issues (not to mention some of the characters that need the help) I've seen the superabundance of network provider mall/strip-mall stores deal with. Hopefully all of these are just remnants of a time we'd all like to put behind us.