Every one of them knows where the door is...

There is absolutely no reason that ground-based conductors won't work for the vast majority of movements that do not require switching. Sure, there will be some added delay when a conductor isn't on site "immediately" to fix that broken knuckle. So what?

Those types of issues occur very infrequently on through movements and it's a waste of resources to have a rider along for such low probability events.

Wanna ride a choo choo? Buy a ticket for Amtrak. Wanna work? Pipe down and get in the cab!