A lot of them cap usage, though (at least officially). The phone card could just be structured as "$X for Y years of access, with a maximum total usage of Z" t

A lot of them cap usage, though (at least officially). The phone card could just be structured as "$X for Y years of access, with a maximum total usage of Z" to get around this. It seems more likely that the difference is that cable companies usually bill later, whereas prepaid phones obviously bill up front.