$100 in US is INR8000 in India, if the job timeline is one week, and they took up 4 jobs in a month that is 32,000. Which is more than the entry level software job salary.
Upwork is a global company, not just the US market, so thinking in local currency won't make sense.
I was on Fiverr 7 years ago I explored it a lot, during my course of finding work there I came across interesting things. There were dedicated shops that took up 10-15 projects a week in the same bracket as u mention, the owner of one such shop bought a Harley Davidson in a year(Harley Davidson bikes cost a lot in India) his shop was 4 fresh out graduates who exclusively built WordPress websites. And there are many such groups.
Also funny enough most of the logo/graphic design/video edit jobs a remixes of PSDs/templates found on envato, freelogogenerator etc. You rarely find quality in such sites, you get what you pay for.