Abstractions are equivalences, not equalities. You shouldn't expect an abstraction to make a linked list the same thing as a vector - they aren't, and they never will be - but they are equivalent for certain purposes, and a good abstraction can capture that equivalence. The performance of those two different collections is not the same, but that's not a leak unless the abstraction tried to claim that it somehow would be the same.
> You shouldn't expect an abstraction to make a linked list the same thing as a vector - they aren't, and they never will be
I would even argue that's the point of an abstraction. Hide the details that don't matter to the caller. If performance is a detail that matters, and the abstraction doesn't capture it, then you're using the wrong abstraction.
