I'll again point out:
Excluding academia, psychologists in healthcare make money by billable hours X hourly fee. That's it. Cost of living, market saturation, etc have almost nothing to do with the offered salaries.
The mentioned reasons are just strong arm techniques.
Well yes and no.
Billable hours x hourly fee - overhead and expenses
We all make a similar hourly fee from the same payor sources in a given area of practice and the country. Cost of living affects overhead (office space ,etc) and market saturation may dictate how much leverage you have in negotiating percentage with a practice group/director. Less incentive to give you 60-65% of collections if there is a line of people behind you willing to take 50%. You can always set up your own private practice, but that is less feasible in some areas of practice than others.