Well, arguably the mezuzot weren't supposed to come with the house at all -- it's not like they were in the contract or anything, and they were left as a convenience, should the next owners be Jewish. The movers presumably considered them more "property of the Jewish community" (including themselves) than "part of the house." But you would think they'd ask first.

In sort of parallel terms (and this is going to sound really dorky) there's a bit in the seventh Harry Potter book, which I just re-read, in which it is explained that goblins consider everything goblin-made to fundamentally belong to them. Humans that "buy" goblin-made items are just renting them until the death of that human, and goblins consider it criminal that humans will such items to their kin (and therefore, the vast majority of human-owned goblin-made artifacts are "stolen" -- this, of course, generates a certain amount of plot, since many of the important artifacts in the story are goblin-made).