> Salaries for developers are well under $150k in most of the United States, for example, and that is for senior engineers

As someone who has hired hundreds of SWEs over the last 12 years from 20+ states, I have to disagree.

$150k is on the lower end for base for a Sr. SWE, and well below the total comp someone would expect. You can make the argument that $150k base is reasonable, but even Sr. SWE in the middle of the country are looking for closer to $180k -$200k OTE.