I think the question comes down to the feed leaving the first box is if a service conductor or a feeder.
If it's a service conductor it needs to be 'legally' outside the building and the PVC conduit won't do that.
A service conductor has no overcurrent protection upstream so if it overloads there's nothing to automatically shut it down before the whole place catches fire.
If the wire is taken off before the breaker it's a service conductor, but if it's after the breaker it's a feeder and only needs physical protection (like the PVC conduit) since it is protected from overload by the circuit breaker.
