At the Bar people starting had to pay! The fee to a 'pupil master', the very experienced barrister whom the newcomer helped and who supervised their work for a year, was 100 guineas (£105), of which the shillings (£5) went to his clerk. He didn't need the money. The pupil could do his own cases after 6 months and earn what he could. If they impressed the pupil master enough,they might be allowed to join the chambers or 'squat' until they could find some chambers which would take them; they couldn't , and can't, practice on their own but have to join more senior barristers in a 'chambers'.
This system, bizarre though it was, was worthwhile. Only the keen ones stuck with it, rather than go into other, paid, employment , they learned a lot, with any luck, and the most able and suited to the rigours and demands of the job survived.
Now, if only the unpaid employment had those qualities, with its hope of a rewarding future, it would be good. Modeller's daughter and the hair stylist are examples of how such a scheme should be.