In almost every case, I'd bet these people don't have $500 is because of their priorities.
$500 is not alot to put aside, even when things are tight, so I suspect it often is a case of priorities.
Personally I don't think many of these people lose sleep over it either (it would be temporary or wouldn't happen otherwise), until the LL is threatening to kick them out, the power is about to be cut off, etc.