I suppose it depends on whether you think regulation should be used to dissuade poor people from buying expensive phones. That seems like a reasonable enough goal, though I don’t believe that’s the proper role of government.
I’ve always bought phones outright, used when finances so dictated. I agree that’s the wiser approach.
Subsidized devices blur the line between a fee for terminating service early, and paying off the cost of the device. Perhaps the former should be banned to encourage competition, and the cost of the device and the service clearly separated. That way it’s clear when the device is paid off and (in my imagined ideal regulatory scenario) must be unlocked.
They probably don’t have to pay the fee. They might owe it legally, but the likely consequences for not paying are some impact on their credit score and inability to get service from that carrier under their own name for a while.