Because very few companies offer relocation. Living on welfare in a paid for trailer on land your ancestors lived on is much more appealing than moving without relocation for worse lifestyle in a rental in low wage work that will result in a lower effective income in a higher cost of living area.
People are often dumb, but they're not insane and over years they do respond to incentives.
People are often dumb, but they're not insane and over years they do respond to incentives.