std::sort only works for random access iterators, but a std::list only provides biderectional iterators. Since it therefore cannot be used with std::sort, it needs its own implementation, which is also likely to be more optimized for a doubly linked list.
Likewise you cannot use std::map or std::set iterators with std::sort. But for these you don't need it anyway, as they are always sorted.
As a side note, there are also std::map::find and the like. These are indeed not required, as you can use all iterators with std::find. But the member function versions provide optimized algorithms for the individual containers, which are more efficient than std::find's linear complexity.
