Gadol, the world is indeed a narrow bridge; people can lose – but also gain – eternity in a moment; chazal say both of those things.
As for OOT communities; who says there are no shaatnez checkers? In established communities I’m sure there are. And if there aren’t, it’s just another reason among many to live only in a makom Torah (and yes most OOT communities are perfectly within the definition of makom Torah, to be clear)