i asked to apprentice for a machinist who makes driveshafts for automobiles; he told me to come back and talk to the boss. there were legal issues / workers comp. issues possibly involved that would prevent me from learning this stuff.
i offered to work for free, just so i could learn how things work. he was a nice man.
but the legal framework prevents me from doing this, as i've asked a couple places before, a few years ago. at least, i think i did, i can't remember. did i ever ask anyone ? i'm sure i did.
anyways, people could just show up and offer themselves to apprentice, and they could sign their own contract agreeing not to sue if they got hurt. as far as if i might hurt someone else on accident, that would be too horrible to think of.