For thousands of years we shit and drank from the same rivers. That wasn’t the most dangerous thing around either, but I’m kinda glad we stopped that too.
Of course, we’re better off today no doubt.
But let’s not act like this is ridiculously dangerous for humans to engage in.
It is though. It’s the mixing thing.
You can order a steak rare at a restaurant, no worries. They won’t serve you a hamburger that hasn’t reached temperature. There’s only one real difference; your steak has a miniscule chance the cow it came from was sick, while that hamburger has the bacteria of every cow that went into the meat grinder.
As per the other comments, we have thousands of cows per bottle of milk. 1000x the risk that someone drinking raw milk from their family farm has.
(Pedantic, but informative incoming)
That’s not the reason.
Cow muscle tissue is dense and difficult for bacteria to penetrate, with a single surface area (the outside) assuming safe handling and “edible freshness”. So cooking the outside to “rare” offers protection by cooking off surface or lightly penetrated bacteria.
Ground beef is soft and porous, with a massive surface area, much easier for bacteria to penetrate completely.
However, that aside, your analogy has a sound basis: more input sources = higher opportunity for corruption.