It's real simple.
When you work (yes, even as a teenager), you get paid. When you work efficiently and with enthusiasm, you build a reputation for others to emulate. When you outgrow that job and move to the next, you retain your skills that you've learned -- especially the bit about working with enthusiasm and efficiency. Pretty soon, all that becomes a habit that you take with you through the rest of your working career.
You continue to get paid and most of the time, you get paid more and more because you assume responsibility and accountability.
That's the way it works. Shielding teenagers from work is yet another draft of wind blowing through the House of Cards that we continue to build.