Depending on who you steal from and how much you steal, you might get some hired thugs (that are actually hired-bloody-murderers) after you.
Which
also doesn't detect circumstances very well in some cases.

Like the situation mentioned in a pickpocket thread - 100 PP, steal a Briarheart's briar heart (killing them), but it's possible to get attacked by thugs "hired" by that Briarheart.
Or the one I ran into doing quests in the Dibella Temple.
Spoiler I stole the statue, to trigger the "do a penance for us". Got deliberately caught, they took the statue back, and assigned my mission. And then I got attacked by thugs on the road, hired by Hamal to punish the thief.
Wait, what?

OP: ownership has always been a little flaky in these games. Like in Fallout 3, with the Ghouls & Tenpenny Tower situation. Convince the tower to let the Ghouls live there, the Ghouls abandon their old subway tunnel lair, and leave all the junk behind.... but it's still all marked as "owned", so that you can't just take it. Ditto for The Family.
Spoiler Wipe them out to end their threat to the nearby village, but all their stuff (in a subway lair filled that was owned by cannibals/vampires) is still owned. Exactly who is reporting the thefts, and why would any of the local "authorities" (villages happy to be safe, Brotherhood happy to have crazies dead) care you're taking their stuff?