My kids all started working the summers they were 15. As the OP can see there are so many options. I’m a proponent of kids working for many reasons. Both of my college grads found real jobs fairly quickly after they graduated in part because they had an actual resume with real jobs spanning 6 years. It can be anything from tutoring to lifeguarding to working in a restaurant or a store…real jobs where you punch a clock and get paid is invaluable and 17 is plenty old to get started. i posted once that one of mine learned a second language during a summer job working with migrant workers and got paid for it and I didn’t have to fund some expensive immersion program. 
Kids don’t learn how to work with other people by osmosis and they don’t learn the value of money until they’ve worked an entire day and find out the money they are paid won’t fill a tank of gas.