Anarchists usually think that a lot of murderers actually get away with it in our actual world, be it through war crimes, neglecting sanitary or safety rules to maximise profit; you can extend this list with a lot of legal murders.

Anarchism definitely does not define a specific rule for what to do with murderers. Different communities might want to handle that differently. They usually think that prison does not solve anything though, and that only the poor get sent there anyway.

I think a mistake is to think that anarchism is a "feature-complete" view of the world, when it really is the realisation that power corrupts, and that we should keep this in mind when organising ourselves. Arguably, over the long run, anarchist views are winning: institutions that prevent - in theory - crazy psychopath from taking absolute power, churches losing power over our lives, women considered as human beings; these are things anarchists have pushed for, for 2 centuries. This short essay might give you more insight: https://theanarchistlibrary.org/library/david-graeber-are-you-an-anarchist-the-answer-may-surprise-you

By your logic, murders don't happen anymore in liberal democracies?

It isn't some deep philosophy indeed. It's very practical and not a church in any way. Anarchists usually don't care about people calling themselves anarchists, but consider that some stuff like counter measures to absolute power that our institutions have, gender equality and some other stuff are things they've been pushing for a while.

At its very core, anarchism is the refusal of any fundamental dogma, and in some ways very related to the scientific method and rationalism. This is probably a more personal take than what I've written so far ;-)

Chill out man, we aren't coming to behead you or anything. <3

All murders happen because of emotional (killing someone in anger), economical (Theft gone wrong) or psychological (Doesn't realize it's wrong) reasons. none of these is prevented by sticking the murderer in a box after the murder.

All of these are prevented by building strong social network to manage any harmful impulses before something happens, which is something any reasonable anarchist would agree with.

Also If you think the list is incomplete then feel free to give another example.

Oh yeah also political assassinations and wars. But your comment already addresses those.

I think a better wording is that anarchy is naive. And I'd rather be naive than accept that this is the best we can come up with, because that's depressing.