@LukeAlmighty Actually we can, there's still a few tribes that still eat raw meat, like the one on the pic.
There was a article(that I don't know how to search) about a nomad african tribe that eat raw meat and they searched for an explanation for that, the reason was kinda simple.
These tribes usually when they kill the animals, they eat right there or take to the tribe to eat(which doesn't take more than a few hours). Because most of the time the animal is still hot the antibodies on the animal carcass helps the body to delay the growth of bacterias and more.
And this is the difference, they kill the animal and eat right there, so the meat itself is clean
About the water I think can be the source or the body of the person grew antibodies to deal with the "purification"of it