Except that even Apple's ARC is not automatic - try passing the pointer to a GArray, or putting it on a malloc'ed linked list or any other data structure not implemented in Swift or ObjectiveC (provided that you compile objectiveC with the correct build flags).
The point is: you can't leak, you can't end up keeping a reference without incrementing the refcount and you don't events have to worry about any of the refcounting as long as the code you write is sound according to Rust rules.
Writing by hand isn't the same.