One possible explanation:
It may be that the place of residence of some people is determined, during their working years, solely on the basis of the availability of high-paying jobs.
Then, when they are facing retirement, the available of jobs is no longer a factor in their calculations.
Rather, as retirees, they are then concerned solely by such other factors as: climate, proximity of family, etc.
Regards,
Those would be half my neighbors here in Southern AZ.