Sincere question: is this a suggestion that locking phones to networks ensures users pay off their devices? In my mind, you could still allow people to purchase and pay off hardware while allowing them to be on a separate phone plan. I.E. buy my phone with a hardware payment plan from T-Mobile but use Verizon -- but incentivize users to be on T-Mobile's network because you get better payment options/perks.

But even in asking that it kind of highlights that their money probably comes from locking people into their network rather than selling hardware...

EDIT: T-Mobile is also probably the perfect example because their network coverage sucks in comparison to Verizon -- at least where I have lived. They probably lock their phones because nobody would use their network (again, at least where I live).