As a fellow European, preventing the value of your house dropping because your neighbors didn’t clean up their front yard.

That does not have to be the responsibility of HOAs. I have had a period where my previous gardener quit and I was looking for a new one; some weeds in the front yard grew too tall. The city sent me an official reminder. This was in a neighborhood without HOAs.

but why would you need an HOA for that? If your neighbor drops their junk on the street you can just call the cops on them yourself