Wil Wade emails me some very interesting points:
As someone who has changed jobs a fair amount and recently, I thought I might be able to give some ideas on why better matching and results decreases mobility. Some of these might be fairly easy to set up tests for. (Note I am a programmer, someone with many job prospects in almost anywhere I could want, so salt as desired.)
1. You think you will find something. Everywhere has lots of jobs posted, so if feels like if you just wait until tomorrow, that job in your area will pop up. Why look at another city, when your city posts 100 new jobs a day (none of which will be good for you, but you don’t know that)
2. Perhaps especially in white collar jobs, you never get a job from a job posting. Never is a bit strong, but your network leads to most jobs. (of the 5 jobs I have had in the ~10 years since graduating, three of those were network based) The less mobile your network, the less mobile you can be.
3. Comparisons are really hard to make when cost of living varies so much. I do not know if the variance in cost of living has increased over the past 30 years, but I do know that it feels really high. As a programmer I easily could move to any of the large cities SF, LA, NYC. But the cost of living adjustment is really hard to make. And currently impossible to make at an I could move anywhere level.