It might open an unwanted can of worms but maybe the drivers could claim they aren’t signing singing along to the radio but are vocalizing actions like Japanese train operators to ensure focus and safety.
Edit: I saw the sing and it opened up my eyes
This could be turned into a game with some kind of narrative like a Choose-Your-Own-E.U.L.Adventure. Players might try to exploit it though, so there should probably be some terms they have to agree to first.