Imagine person A lives in an area with a high cost of living and gets full salary. Person A is able to purchase a house at a high valuation relative to the national average. Person B in a rural area is able to buy perhaps as nice a house on a smaller salary in a below average market.
Now look at the options available to these two people when they want to move. Person A sells at market rate or perhaps a little below and can move to a lower cost of living with a relatively large pile of cash. Person B has no such option. The real estate market arbitrage is available to person A and not to person B.
The salary of person A looks like it produces options and upward mobility. The salary for person B seems to have more limitations.