How is place=municipality used correctly and are there country/state-specific rules not to use it at all?

[Vinzenz_Mai]

First:
Yes there are country and even state-specific “rules” for place=municipality

@Harald_Hetzner

But for Germany and Austria, I would say that the administrative structure is pretty similar.

That’s not true. It’s not even true for Germany alone. There are differences between the federal states as well

In the smallest federal state of Germany there is no node with place=municipality and there should be at most three :D.

The wiki page you quoted is at least misleading - and is different from DE:Key:place - OpenStreetMap Wiki

Der Knoten sollte an einer Stelle liegen, die für den Ort als zentral angesehen werden kann. Dies ist nicht notwendigerweise das geometrische Zentrum. Es kann sich auch um die Dichte der Besiedlung oder einen zentralen Ort handeln, der wichtig und bezeichnend für den Ort ist.

This page shows additionally where municipality comes from: More from the admin_border=7 than from the German translation of municipality. It may be the same problem that was discussed in Admin_level, boundary naming on OSM.org and translation

@Harald_Hetzner

place=municipality: Do no use. Use boundary relation instead for any information related to a municipality.

That was discussed a tiny bit at Talk:Key:place - OpenStreetMap Wiki