No Sorted Set (Red-Black Tree)?

This is seriously concerning to me, how is there no implementation of a sorted set in Unreal?

I have to use std::set<> because of the lack of what should be part of Unreal standard containers.
I’m talking about red-black tree O(logn) insertion and access.

No, a TArray<> that you call Sort() on is not a valid method, that is extraordinarily inefficient, and neither is finding the index of insertion with a custom binary predicate on a TSpareArray<>, hoping that there is an empty slot before the actual index of insertion.

Can some staff member please explain to me why this sort of basic container functionality isn’t implemented?