Ignoring for the moment the question of Are You Human or Are You Troll, that is a terrible analogy. Digital and analog television are encoded and transmitted completely differently over the air; in contrast, from the phone's link layer perspective, any two GSM carriers are indistinguishable from one another, especially if both carriers are transmitting in the same radio band, and ESPECIALLY if both carriers are in fact one and the same from a physical network perspective, as AT&T and the MVNO Straight Talk are!
My situation with the phone would be more like having a digital television set that was programmed by its manufacturer to only allow you to watch specific channels and lock others out, even though the television set is physically and in all other ways capable of allowing you to watch the non-whitelisted channels: it's simply an arbitrary software lockout. The "unsupported" channels aren't doing anything funky or being encoded and transmitted some other way.
Or it might be more like an IP router -- for the sake of this example, let's say it's a boring sub-$100 consumer-grade router/switch/wireless-AP thing -- that will only allow you to use it with certain internet service providers, even if another "unsupported" ISP encapsulates and delivers its traffic to you in exactly the same way the "approved" ISPs do. Let's say the ISP expects the customer's gear to speak direct IP-over-Ethernet to it (and not IP-over-ATM, PPPoE, or any number of other possibilities), and that the "supported" and "unsupported" ISPs both also run DHCP servers. The "unsupported" ISP fails to work with the router, not because it is doing anything out of the ordinary when compared against the set of standards that the router was manufactured to support, but rather because although the router accepts the DHCP responses from both ISPs, it willfully ignores the default route passed to it and overrides it in the routing table with a hard-coded IP address that it knows the "supported" ISP will have a gateway responding on.
That's what's happening here with the phone: it's overriding the APN settings with the AT&T values and not allowing me to change them. Since it is an unlocked phone, I not only consider the fact that AT&T's iOS carrier profile is the agent "doing" (in the loosest sense of the word) the APN overriding immaterial (after all, Apple's the one who handed those keys over to them...AT&T wouldn't have that ability unless Apple engineered it into the system and said "here you go"), but Apple *specifically* shouldn't be giving their carrier partners that kind of control over *unlocked* models.