I can't prove anything, but I've always suspected that folks who are acclimated to eating things like raw eggs, or are regularly exposed to stuff like chicken guts from butchering, and who have to shovel poop, that sort of thing... have healthier gut bacteria and immune systems. I think a sort of resistance to foodborne illness can be acquired by simply being around the animals you eat. In today's sterile commercial food chain we see a lot of foodborne illness that could probably be avoided by NOT being so sterile.I eat a lot of eggs in a raw state (homemade mayo etc) and have never gotten sick that I know of. Not from my backyard eggs, eggs from other backyards nor store bought eggs. Well, for whatever that is worth anyway.
I still sanitize my surfaces and cook my food well, though.