I recently had a trip to NL and was very surprised to see jobs for children being advertised there!
There's a lot of kids stocking shelves in the stores here. It's a great way for them to be responsible and earn a few extra euro. I think it's great that the Dutch don't treat their 15 and 16 year olds like babies, like American parents do.
I just wish this were available to more families.
The (possibly completely incorrect) impression I get from speaking with Americans I know who have moved here, or I work with, is that nobody really works until they get to college unless it's a paper round or it's at your parents business. It almost goes without saying then that most people would be pretty infantile if they don't start work until they're almost mid-20s.
It was a nice surprise to see teenagers working in my local brewery this past weekend, collecting glasses, clearing and cleaning tables, etc. They were probably between 13 and 16. Not allowed to serve alcohol until they are 18, and can take on the personal legal responsibilities for Responsible Service of Alcohol.
Most jobs for teenagers here are in fast food service - two of my friends have mid/late teenagers working these jobs. Most jobs in retail, at least near me, seem to be taken by adults.