It'd be extremely out of the norm for telco companies. Tin Can uses the calls and voicemails to collect data on children and sell that to others. That has zero to do with lawful interception. The moment Tin Can becomes popular enough you can bet that the government will be snooping those calls too
It would be pretty spooky if your voice managed to come out the other party's telephone without ever having been collected into and processed by the telephone network. Taking audio from one place and transporting it to another is what we pay it for.