Because of the small populations of these towns, the businesses that aren't absolute necessities (grocery stores, gas stations, bars) see very little foot traffic, so they need a very small staff. Many times, those stores are just run by the owners themselves. And when you look at that as a whole, it adds up to a small handful of businesses with a small handful of employees to sustain an entire community of people. Not counting meth labs, obviously.
Ain't nothin' in that barn 'cept cows and love, son. Move along.
Unless the town has a local factory, the aforementioned grocery stores and gas stations are often going to be the most likely places to find a job -- they're the ones making money. My town has three gas stations, one grocery store, and about 2,000 citizens ... a large portion of whom currently have applications on file at all four places. Since the demand for employment is so high and the supply is so low, the businesses are now free to drop their starting pay down to "fuck you and any pets you might have."
Everything is minimum wage, because not only can anyone do those jobs, if someone complains, there's the door. They could hire someone new by the end of the hour. And you can bet your ass that if you're looking for an evening shift, you're just screwed -- it's going to a high school kid because they are somewhat disposable. You don't have to worry about vacation time, seniority, babysitter problems ... many of them are already on their parents' insurance, so you don't have to give them that benefit. Plus, they're still young enough to work with a hangover and not think anything of it.