As I've understood it, one reason they will refuse to do anything about those cases is because they can't really differentiate between "this is dangerous" and NIMBYs who don't want traffic down their quiet suburban street.

But also, if people are actively complaining about it, maybe that's a good indicator the street shouldn't be used as a thoroughfare in directions. Being a little bit faster isn't a good justification, and back road shortcuts aren't something that should be widely advertised to tourists and visitors.