That's kind of my point - Owning it is not a crime. If police finds a copy in your house, you're not automatically going to jail just because you have it. At the same time, its publication and sale is either prohibited because of copyright issues or under laws which prevent sale of Nazi paraphernalia.
Incidentally there isn’t a single country (as far as I could find) where owning Mein Kampf is or was illegal. There’s a common misconception that its possession is or was illegal in Germany. However, this was never the case. Until 2016 the state of Bavaria owned the exclusive copyright and prohibited its publication. But that’s it.