Photography is cheap. Everyone has a camera.
Photographers don't like to hear this -- and I say this as a photographer -- but most people are OK with reasonably shitty photos. They don't care if you want to spend an hour touching something up then charge them for it. They'd rather have something poorly framed and overexposed shot on a smartphone and get it free.
I'm lucky in that 99% of what I shoot is part of my day job, so I get paid regardless. But if people ask me for photos that I've taken at work or incidentally during a work shoot I just send them jpgs free. There are a lot of photographers like me who do that, too, which probably also hurts the market for people asking money for photos.
One recent example is I was shooting portraits for a marketing initiative at work and a passing student asked if I'd shoot his headshot for a resume or something. I had all the gear set up so I said sure. It took like 10 minutes later to edit and send him the photo, so it didn't matter much to me. But some people try to charge guys like $100 for that simple task, which is silly.
I don't really use them but often I think it'd be nice to have them to get the "boring" shots I really need. Like when doing event photography I know I need to get some shots of the sponsor tables. It'd be nice just to have someone cover those required shots so I can focus on getting the more candid real moments.