People feel like they _have_ to live in NYC/SF/LA when they make peanuts. If those people moved to the Midwest they'd have much lower CoL and probably still around the same pay. Amazon pays $15/h wherever you are.
The other problem is that if you want to "better your life" and stop working at Amazon for $15/hr, historically you had to go somewhere where those better jobs are (often NYC/SF/LA, depending on industry). Maybe with remote work becoming more common this will change, but telling people to live in low CoL areas unless they're already making a good income puts a serious damper on social mobility.
> historically you had to go somewhere where those better jobs are
There are plenty of good paying (maybe not FAANG's 500k salary but 6 figures nonetheless) jobs in Chicago, Atlanta, North Carolina RTP, Columbus, etc. The biggest contributor to social mobility is getting a good degree at a good school. If you get any engineering degree from any decent state school - doesn't matter mechanical or computer or chemical or whatever - you're making good money.
If you are even luckier and can be a developer in those cities making 150k-200k you feel like royalty with a ton of extra money to travel often.