But then it comes back to "well if their lives are at risk staying there, why don't they go somewhere else?"

1) Because they're poor.

2) People don't move as groups. Ever seen rich white people move into a working class neighborhood and gentrify it? Everyone that's forced out during the process spreads to the wind and the community dissolves.

There has to be something special about the neighborhood itself to keep them there.

Yep, we've already discussed it. Interpersonal relationships and family history. It's the same reason that people stayed in Coalwood, WV after the mine closed. It's the same reason people from small towns almost always stay in their small towns, even if they move away for college or the military.

"because they grew up there" is a cop-out

No it's not. It's reality. That's how pretty much everyone exists outside of a minority of upper-class people who hop from hip city to hip city. It's not a cop-out if it reflects reality, and that's the reality for almost everyone who isn't a 'young professonal' looking for the new hip thing.

but most of the central characters are in the same generation you assumed I was part of.

Story time. Of all my friends from college, nearly all of them returned back to their small towns after college was over...some of them even work retail to stay in those small towns despite having STEM degrees.

It's real and very common human behavior, I can peg your approximate age and social class because you're insulated enough from it to not have seen it...but just because your class has insulated you from it doesn't mean that it doesn't exist or isn't common.