Gas Station Slots Machines

Has anyone else been to a gas station that has a dedicated (often hidden) section filled with slot machines or maquinitas? So I've seen these around the past few years, and I imagine they have been around a lot longer than that. But, can anyone explain what these slot machines are? Do they pay out real money? Some of them are out in the open, so it it were illegal, they would get busted. I cant imagine who would want to gamble in one of these.