I'm not sure that's true, but I will admit that most of my friends work at FAANGs (outside the bay area). So let me add that I know at least one senior engineer at a non-FAANG tech company that left a $300k job for a "significant pay bump".
Frankly, no large tech company could survive if it didn't pay competitively with other large tech companies.
I fully agree that pay is less in small, non-tech companies in rural areas, but I would be surprised if such businesses hire the majority of developers. Big tech hires a LOT of engineers.
Alphabet - 98,000 (2018) Facebook - 35,000 (2018) Apple - 123,000 (2018) Netflix - 5,500 (2017) Amazon - 647,500 (2018)
Total - ~909,000
That is total number of employees worldwide. so lets conservatively take off a third. Also Reasonably only a third of those employees (probably a lot less at amazon) are actually developers. That gives us ~200,000. The Bureau of Labor statics says there are 1,200,000 software developers in the US in 2016.
FAANG does make up a lot more software development jobs than I thought, I would have to say a significant portion. Very interesting.
Sure, the lone "web developer" at a small nonprofit might make $80k, but at a FAANG? Please.