Such good comments (peace to you all!)... and I particularly like/agree with dear LWT (peace to you!). My TRUE answer, however, would be different from most: he's 15 and, therefore, still a minor and, therefore, unless he's being abused (which does not really include being forced to learn a trade) or in some kind of danger, he is at his parents' mercy, right now. Right NOW... NO ONE should tell him to do anything other than obey his parents.
Ms. Josie, my dear, dear one... I know how this concerns and frustrates you (I would be, too!), but I would tell YOU... out of the greatest wish for love and peace... to mind yours, my dear sister. 'Cause Lord help the person trying to tell MY minor child what is "best" for him/her while he/she resides in MY house. And I can't imagine too many here disagreeing with that.
Now, if one wants to say something like, "You know, if, when you turn 18... or get emancipated... you still have questions... I would be more than happy to sit and have a talk and tell you what I know/think. Until then, though, MY advice is for you to suck it up and listen to/obey your parents. Because, right now, they are the ones who're providing for you and your needs. Your roof, clothes, food, health, etc., all depend on them, for now. So, you OWE it to them to do what they say, so long as you're not being harmed. And learning a trade, while it might seem hard now, will help you in the end, even if you choose to do something different later. Right now, it puts money in YOUR pocket." That his job may be illegal is his, his parents', and/or his employer's problem... and responsibility... and no one else's.
Dear one, there is such a thing as interfering where we shouldn't. Again, unless a minor is being abused/in real danger (and possible indoctrination into a cult we hate doesn't qualify)... we really must butt out.
I hope this helps and mean NO offense... and again, wish you all peace!
A slave of Christ,