Yes, so now we have this split where you can buy equipment from a whole range of manufacturers and suddenly the phone company doesn't care at all what crap gets on their networks.

This to me clearly indicates that the carriers at least have the option to ensure that the equipment connected to their network is up to certain standards. But since they don't car e (they never did) they'll be happy to sell you a phone from some manufacturer that is most likely not going to outlive the contract because of the extra margin they make on that phone.

So either they should take it back for some residual value (which they can then try to recover from the manufacturer) or they should ensure it keeps working properly.