The only problem with your examples is I can't go an purchase any phone - I have to go get a Verizon-authorized one.

The cable company doesn't dictate that I use a certain TV, BluRay player, or otherwise.

Walmart doesn't dictate that I can only use Great Value products.

The power company doesn't dictate what light bulbs I buy, or what brand of microwave I plug into the wall.

But Verizon does. Verizon dictates that I will be using a Verizon-authorized phone. Sure, I pay Verizon for network coverage (which, by the way, in their own terms and conditions they cannot and do not guarantee, so there's no real "we owe you network coverage" anyway), but even if I want to dictate how, where, when, and with what equipment I chose to use their service, I mostly cannot. I am at the mercy of the signal, and very much at the mercy of their equipment.