Bass Wear - what is causing this?

I noticed this wear pattern between the neck and the horn on a roughed up bass last week and assumed it was just someone relic’ing theirs and went to town with a grinder.

Now I’ve seen this wear pattern three times in the last week. Does anyone know how this wear happens naturally? What am I missing…

(Not to mention that the paint/lacquer being used now seems too high quality for these wear patterns to continue with newer instruments.)