I think that’s because it (¿almost?) always splits “is not” in two parts. Compare “If x is not y” with “if not (x is y)”.

> for some reason, "when" in ansible is also very weird

When feels weird to me, too. I think that is because “when” often implies something will happen, but you don’t know the exact time, while “if” means you don’t know whether it will happen at all (compare “when it rains” with “if it rains”). So, using when to describe a trigger is fine, but to me it doesn’t make sense as a statement in an imperative programming language.

> just reading the README felt very weird.

I had to check, and yes, there is a README.md, and no LIVREMOI.md.