I was a substitute teacher for two school years. Remember how mean we all were to subs in school?
The really horrible thing wasn't the kids though, but that I was essentially a gig worker (this was before Uber was widespread so the term hadn't really taken off). I had no guaranteed hours. Instead, schools in the area would post to a website when they needed a sub. Those jobs would be put on the site and the first person to pick them up would get them. This meant usually a couple hours a night refreshing that page, waiting for jobs to trickle in, and pouncing on them. My only computer at the time was a crappy little 7-inch EeePC with the tiny tiny keys. I did end up automating some of the tedium but I still had to actually decide if the job was worth it -- some of the schools were so far away that it was barely worth it after figuring in gas money, and some classrooms were such disciplinary nightmares that it wasn't worth my sanity.
If I didn't get a gig the night before, I would need to wake up at 4:30am to do the same: shower, eat, get dressed, wait for the last minute jobs to show up, hope to snag one, then jump in the car and drive hopefully in time for first bell at about 7:15-7:45am (differed by school). Sometimes I would do all that, driving 45m to some rural school, only to find later on payday that they had cheaped out and not paid me for a prep hour, saving themselves pocket change in order to screw me out of 50 minutes of pay. With hustle, I could usually get work on school days, though probably every other week I'd have a day where there was no work (and therefore no pay). I had to wear a suit and tie every day as well (or else schools would complain to my company that I was unprofessional) even when I knew for a fact that the school had a more casual dress code, or did "jeans Friday", etc. When I was really desperate (if I'd had a few no-work days that pay period, for example), I would sit at the computer until lunch time hoping to pick up half-day gigs. Again, none of this time looking for jobs is compensated in any way.
It was a truly dystopian experience and is the reason I have never ordered DoorDash, Shipt, TaskRabbit, etc. and have only used Uber in dire situations where I can't take public transit and I don't have access to any vehicle or the ability to bum a ride from a friend. Treating employees this way (no guaranteed hours, unpaid scrambling for individual gigs, etc.) is simply evil.