Because Git is distributed, there's no "a branch" foo or whatever; that's a very pointedly centralized-logic, non-DVCS way to treat Git. If Alice has a head nam

Because Git is distributed, there's no "a branch" foo or whatever; that's a very pointedly centralized-logic, non-DVCS way to treat Git. If Alice has a head named "foo", Bob can fetch Alice as a remote and get a remote-tracking head "alice/foo", which has no bearing on any head named "foo" Bob has; it's just a view of Alice's state. You can see why you'd want to prune these on fetch, if you want your refs/remotes/alice state to mirror Alice's state; this means removing "alice/foo" if "foo" on Alice is removed. You also might not want to, that's fine. But if you use git fetch as though Git were a DVCS, this is exactly the natural behavior; it's only when you imagine Git is centralized that it starts seeming strange. So the answer to your final question is "this is not how distributed VCSes work". (Just don't ask about tags. Ugh, what a nightmare! To be fair, the idea is that you don't go around fetching tags.)