Jeez... Supermarkets? Amusement parks?! And I lol'd at paper routes... I would've killed for that in my teens. Grocery stores and other indoor work was usually taken up by the girls or by whoever knew the owners (good ole boy system...).
Where I lived you couldn't really work legally until about 17 or so, and even then you had to be extremely lucky to have a handy down car for transportation; there were no buses (except for school) or taxis around. Before going to college, I was working in the most country of Mississippi jobs: baling hay(everyone was too broke to afford proper equipment), car repair outside a relative or friends garage, farm building construction, cutting grass along highways, wiring and posting horse, hog, barbed wire fences, and countless other outdoor labor work all done in mid Mississippi summer, work in winter was hard to find; and I wasn't dirt poor by any means though, this was just to earn money. There was other work like folks paying to move, painting and drywall, insurance jobs needing more men mostly for stuff like demolition or removing debris caused by storm damage, etc., or work with ERDC if you got lucky. These I would have for saving money for things I needed or wanted (like bass gear!), but there wasn't much work elsewhere...
I didn't have my own cell phone or car until about 19 (old busted Chevy and prepaid cell phone cards FTW!!!), and I got my first real job shortly before 20, at Cowboy Maloney, lol... Since then I've been working at various internships and/or volunteer work, bars, or retail; I'm 23 now BTW... School was really my way into what I'm doing and where I'm living now (Jackson, MS). During my teens though, if you lived out in the country, you were $h!t outta luck...