How much "buffer" or margin of error is in food safety guidelines? When I read food safety guidelines, I always get the sense that I should run for the decon shower if I even look at a piece of raw meat. I have to fight the urge to sprint home with my groceries lest the eggs become poisonous on the way. If I thaw meat from the freezer, I worry that one misstep will kill me.

But rationally, I know none of that is true. Aside from the fact that I've been cooking for myself for decades, and I'm still here, we simply wouldn't be here as a species if it were that hard to cook safely. And then there's this thread from a couple of years ago, which seems to say that there's a fair amount of subjectivity in food safety procedures. (But this thread takes a stricter line.)

So: how much difference is there between official food safety doctrine and actual danger? Are there rules that are just oversimplifications in order to minimize human error? 

Update

This is not a duplicate of this question. More specifically, the question is similar, but the accepted answer on the other thread doesn't actually address the question of fault tolerance.
A lot of the "time out of fridge" and similar guidelines must have quite a lot of buffer in a cool domestic kitchen compared to a hot commercial kitchen for which they're written. This is because the temperature is the food is what matters and that will change much more slowly is the ambient temperature is closer to fridge temperature. There's less margin for error in the temperature something must reach to be safe, and even less in things like hand washing and not preparing salad with the same tools as raw chicken.A lot of the commercial rules are about proving it's safe as well, even if shifts change. 

Much of the advice given here quotes US FDA rules, which go further than many other countries. Recently we had a discussion about Australian guidelines on cooling hot food, which allowed considerably longer. The US still has a higher incidence of food poisoning and especially botulism than many other developed countries, even though it had some of the strictest rules.