I had three hot dog carts in NJ when I was in high school. I made great money that's how I bought my 911. A lot has changed since then. I am not sure of the requirements now a days or in California but as other have said it will teach them some basic business skills and how to deal with the system. Another business that high school kids here in NJ do and seem to make good money is fruit trucks and ice cream or water ice bikes.