Times have changed...Before it was mandatory for nurses aides to be certified, I was one at Willow Manor in Lowell, Mass, for a summer, and I was 17. Then I worked at a bank. I bought my first car, Cherry Red VW Bug....
In the early 80's ., many of my friends, worked at Fast Food restaurants, grocery stores, whatever.
I think because of OSHA a teenager cannot use any of the machines,, and of Alcohol and Tobacco Compliance Laws, you have to be 18 to run a register .