I must say this is a very interesting topic and the responses have been very interesting as well. I actually read every reply. So, I've decided to give this some thoughts and also render my honest opinions on this issue.
I agree that it is appropriate for a teenager to ask for money from his parents. Better to ask them than to ask someone else anyway. But I know why he is reluctant to ask for some money. It is not always an easy thing to do. He may feel that they will deny his request. He may feel that he hasn't contributed enough to earning any money in the house and that it might not be a good idea to "take" their money. He may also feel embarrassed to ask for money when he is already somewhat an adult--at least in the Hmong and social and moral senses. In short, he feels weak and powerless for asking. Just a man kind of thing, isn't it?
But there are things the boy needs to know. He may ask for a certain small amount for good reasons for certain occasions only and stop there. He should not ask for large amounts without reasons. He should not keep asking for money over and over again once they have given him money one time. He should not be a chronic "asker." Too much can turn him into a beggar in some sense. And he may be viewed as such. Plus, he, too, may develop a habit of asking for money every time there is a need for money; and he may not feel obligated to work and earn his own.
Sometimes we feel comfortable sharing our feelings with outsiders. So, we don't tell our parents our true feelings or true needs. They may be waiting for the day we turn to them. But we must remember that we should always contribute or reimburse or return if we have taken or plan to take anything.
There are other issues related to this, e.g. working odd jobs, even doing something for the parents for a little allowance, or telling the parents the boy needs to borrow some money. But those are strategies on how this 17-year-old can go about getting some money, not whether it's appropriate to ask for money from his parents. I won't discuss them now.