I don't know, because I rarely go to fast food places. But yes, I have noticed workers seem older (or simply old). I rarely see teenagers working at anything.
Like you, as a young teen I sold newspapers either at busy street corners, or substituting for friends in delivering papers. Also mowing lawns or washing cars for neighbors. As well as sweeping floors for shops. After that, my first check-earning job was at 16 working part-time after school at a sign-making shop, learning machine skills like operating bandsaws, routers, torches etc. Those skills have served me well over the years.
Teenagers now seem lazy and uninterested in learning a blue-collar career. They want a fast buck but won't stick to working more than a few days. All this has gotten worse over the last 30 years. Mostly due to liberal Democrat policies that encourage gimme-dat thinking.
All they want to do is become ‘RAP STARS’ or play basketball, football, or whatever sport. American Idol has helped ruin this country’s youth.
Or sell drugs.................
There are many more legal restrictions that closed off jobs to teenagers since the 50/60/70s.
Do gooders protected the kids right ought of opportunity.