Hey Brian, just looked and your post has over 2,000 views so far, I take it all back, brilliant subject mate ha!
I've often wondered about the legality of this new trend in pricing, particularly for essential goods such as fresh food, and there you have pointed out a very valid concern. You can legally be working full time with children and a household to take care of at 17. I'd love to see a group of under-18s performing some stunts to raise the issue and embarrass the supermarkets publicly.