Honestly B-Cats, most people posting jobs don't know if they're paying or non-paying so you'd just end up with a bunch of people claiming they're paying gigs when what they mean is they'll pay you when the game is finished and they get a publishing deal from Sony, or the Kickstarter is successful, or the other game they finished work on sells millions, or you get percentage of profits, or you get percentage of profits AFTER they reach an unspecified threshhold which pays off their debts, or they intend to pay you but they're a student so they don't have much money right now but if you show loyalty now they'll be able to pay you back when they get rich off their Twitch thingy(damn kids these days), or they're a non profit so they can pay you but you'll be taking money from the children their group supports, or they will pay you with software licenses which may or may not be pirated, or they'll pay you back by making you a website or some other service, or they'll pay you with advertising or just tell all their friends who have money, or they have an "indie budget" so they'll pay you a couple of bucks each week if you hit your milestones, etc etc etc.
Or maybe they have money and will pay you. I like those ones 🙂