Suppose we have a team of experts busily analyzing every single state of the code. They are reading/valgrinding/fuzzing/etc.-- in real time as the intermediate developer writes code.
Each time the developer tries to compile, the team quickly votes either to a) remain silent and leave the dev alone, or b) stop compilation because someone thinks they've discovered an invalid read/write or some other big no-no that the compiler will not catch (but the Rust compiler would catch).
If they choose b, the experts stop for a bit and discuss the clearest way to communicate the hidden bug. Then they have a quick conversation with the intermediate developer. Suggestions are made, and the whole process repeats.
Is this process substantially faster than just learning Rust?
Edit: clarification
It is misguided to say that recursive data structures should be easy to write. They are difficult to reason about and the Rust compiler is right to point this out. CS is not engineering, you should be writing those trees with a pencil on a piece of paper as Dijkstra intended, not in C.
And is your hand-written C implementation going to be safe and correct. You didn't mention any kind of locking or atomic operation, so is it going to unexpectedly break in a multithreaded environment?
The concepts of Rust are definitely more complicated, but in practice it just means that C makes it easier to shoot yourself in the foot. It's easy, but is that really the most important thing here?
In the same vein, driving on a modern busy road requires you to know about lanes, speed limits, various signs, traffic lights, rules of turning and merging, etc, etc. A road without all of that, where a steering wheel plus two pedals suffice, of course still allows you to drive, and drive fast, but it requires much more attention from a driver; many driver's mistakes are noticed later, and lead to more dangerous accidents.
This assumes a self-balancing binary tree must have nodes with parent pointers. Without those you don't need reference counting and without that you don't need `RefCell` either.