However, as more and more companies adopt regional cost-of-living adjustments for salaries, domestic "outsourcing" (i.e. preferential hiring of employees in lower CoL areas) is likely to increase. Assuming developers in Ohio are just as skilled as Bay Area developers and a two hour timezone difference is easily surmountable, why would Silicon Valley companies not preferentially hire Ohioans if they can pay them 2/3rds as much as Bay Area employees? A $200k salary in lower CoL parts of the country goes much further than a $300k salary in the Bay.
[*] That said, even in high CoL parts of Western Europe, tech salaries are far lower than salaries in high CoL parts of the US (e.g. developers in London make on average ~70% of NYC salaries [0,1]). For certain tech companies on the East Coast, a 6 hour timezone difference might be acceptable for such a dramatic reduction in labor costs. Imagine how much lower salaries are in lower CoL parts of Western Europe.
[0] https://www.levels.fyi/Salaries/Software-Engineer/London/ (median compensation: $133k)
[1] https://www.levels.fyi/Salaries/Software-Engineer/New-York-C... (median compensation: $188k)