Examples of work that I use it for are simple html/css stuff that just needs to get knocked out prior to integration into an app. I'll pay between $300-500 from some straight forward design to html/css conversion. I want it to be worth their while.
Also, I've use it frequently for GIS work. I'm just not proficient in it and would rather pay someone that is. I managed to find an incredible person on upwork and give him the specs for each project before I quote my customers. He sets the price for the GIS components and I routinely encourage him to charge more.
So to be clear, I don't use upwork to find a deal on the project (no doubt a ton of people do). I use it because it is a platform that can keep talented people busy and available for the next time I need to rely on them. I'd hire a full time GIS expert if I had steady work for the, but I don't so going with a subcontract makes a lot more sense.