Why does "You have not to do it" mean "You don't have to do it"?

Question

I'm requesting you to do it .

I'm requesting you not to do it.

Both make sense. The second one doesn't mean that "I'm not requesting you to it" rather it talks about prohibition. But,

You have to do it.

You have not to do it.

Why does this sentence mean " You don't have to do it"? Rather it should mean that " You're forbidden to do it".

I'm not a native English speaker. Maybe that's why I'm missing something. Please clarify with proper explanations.

Answer 1

As was discussed earlier here, You haven't to do it is not very idiomatic nowadays, but when it was in more common use, mainly in British English it had the sense 'You don't have to do it."

You just have to accept that, in English usage, have to always means that something is required or necessary. The negative version is must not, unless you use it with a negative verb such as have to stop, have to avoid and so on.