> Why does this happen?

Inexperience.

Come on, really? There are plenty of tools to keep code legible in any language: linters, documentation comments, design patterns, idioms from authoritative references, etc.

Every time I see code that doesn't really "fit in" with more experienced code in that language I already know it's gonna be wrong in other ways despite technically "working".

I've too suffered from the neuroticism, imposter syndrome, and egotism of being new at something, but damn can't we just admit this? Guaranteed everyone who isn't a developer sees it and has to deal with it even outside the code itself.