I don't think they stopped being teenager jobs, I think the education system across America failed to keep up with the world. Some schools can't even do 5 day school weeks anymore, and the switch to standardized testing may have been in good faith but it just led to less time for practical skills to be taught.

Imagine if every high school had the budget to run a modern, staffed programming lab, garage, chemistry lab, hell astronomy lab? If kids could get hands on, across America, at age 13? I desperately wish I had Musk levels of wealth if nothing else so I could just start plopping labs across middle America, where as a child my own craving for a hands on education was never delivered by my public schools.