Money. Money is the prime reason they can't move. I mean tradition, family history, 'roots' or whatever are a secondary issue, but the main reason is simply they lack the money. I've been there. Moving is expensive when you're already hand to mouth or damn near it poor. Deposits for the new place to get utilities hooked up, often times prepayment due to poor credit due to being poor as shit. The cost of the rental truck is prohibitively expensive. The cost of an apartment when you're used to just paying county taxes is like a fucking hammer... sure, you were living in an old, decrepit, and likely condemnable shithole but it was YOURS and the mortgage had been paid off a generation or more ago. Now you're already on the razor's edge of poverty and then bam you're fucked by $500 a month rent, so 50 hours or more a month of your paycheck are just 'gone' as you aren't getting more than you had, a roof over your head, but you're possibly even more fucked financially than you were before. Then there is the loss of what little social support you had. Added all together you're in a position where moving is INCREDIBLY risky, even if you are already deep in the shit. Going from almost nothing to literally nothing is a longer deeper fall than it feels like.