That is, certainly there's the potential for abuse, given subjective debates about what constitutes robust enough training. There's obviously real costs to taking on an untrained apprentice, and fully training them up in terms of both time, lost productivity, etc... But rules put in place to provide exceptions here could be gamed by employers to put in place sham training programs that don't require that much effort solely as a way to lock in new hires and depress wages.

I don't agree that the incentive is always there for the company to train well. There's an incentive to free-ride, not put in the effort in training, and then go poach employees with slightly higher pay because you don't have the underlying costs associated with training.