isn't it because there are too many contradictions and ambiguity? the reason it works for humans is because we don't apply everything at once either.

No, it's more than that. We can't remember everything. I hired, say, two years ago; as part of my onboarding process I had to read a bunch of policy and procedure documents, which were full of stuff that I didn't understand because I wasn't really in the context yet. So at the time, to me, those documents were full of arbitrary text that I didn't really understand. Some of it was rules that I had to follow, but at the time I didn't understand why, so it's just arbitrary rules.

How many arbitrary rules can you memorize? Do you even remember them two years later? If you do, then we can get to your statement.

And your statement is true. Humans do not run every action through a memorized list of rules, to see if any of them block the action. We don't. We're not going to, either, no matter how badly the policy manual writers want us to.