Earlier quoted context omitted.
If the telcos had their way, once your contract ended the phone would vaporise before your eyes.
If that's the case, why don't they already do this? It's totally feasible to design a phone that will brick itself when your contract ends. There's no legal impediment to doing it either.
It could be argued that Apple were already doing this. Remember their updates that knowingly slowed down older phones? They claimed it was for performance reasons, but nowhere informed the user of this practice... Src: https://www.techdirt.com/articles/20171222/15380038868/apple...