You think Apple might have launched on T-Mobile, the last-place network?

Nationwide wireless networks are extraordinarily capital-intensive. Absent a massive technological shift --- which may be coming and which AT&T and Verizon are powerless to stop --- there are always going to be a (1) few (2) very large companies providing cell coverage. It may be more expensive to launch a nationwide wireless network than it is to launch an airline.

Meta, responding to your aside: respectfully, no. I'm trying to avoid typing for the sake of typing. I asked a serious question; you answered it; I responded to it with my take. That's how the system should work.