On a global marketplace? $100/hour is a ridiculously good rate for a large % of workers. Maybe not in SF or Tech Hubs but for a graphics designer in India, or Eastern Europe?
You are conflating price and quality. If there are two top level people equally good one will undercut the other. And if one lives in Bangalore and the other in SF the first will undercut massively. SF living expenses are an exception on a global market place.
High end goods and services are not races to the bottom.
For example, when was the last time you saw an airline undercut their competitors' first-class ticket price? How many sports-car manufactures get in price wars with their competition?
If your services are supply-constrained and there is a string market, you can charge whatever you want (to an extent, at least many times your cost of living), your cost of living doesn't matter when setting your prices in that situation. Your value is what the market dictates, not how much it costs you to buy a loaf of bread.
Take the very same individual and place them in India or US, or even in a high or low CoL area in the US and they would charge differently; but their work is still the same. So you're not really getting what you paid for, you're paying for many externalities.
I’ve encountered offshore devs that are actually quite good... they are by far the exception, but they also charge much more than the run of the mill folks that you’re likely to encounter.
Those type of people arent going to be on a site like upwork, but they make a hell of a lot more than $100/hr.