This only works with a lot of government support. If you don’t have the government’s ok to take more of the trainee’s surplus in year three than you could if they could just leave why bother training them in year one or two when they’re bloody useless or of marginal value? Unpaid internships exist for the same economic reason; for a long time in many fields the training being provided is worth more than the labour of the trainee. If you can’t get a return from the training why bother? That’s where the government comes in, either by allowing those kinds of contracts or by mandating apprenticeships or levying industry wide “taxes” so everyone pays for trainees’ development and gets the return from it more or less equally. Otherwise the logical thing to do is let someone else pay for the training and then immediately hire away the trainees without paying the costs of the training.
