A similar example is posted there, just read it. It's best to read about the problems of concurrent containers, because you clearly don't understand the topic.
I've already done all the things you claim are impossible. That's how I know what you're saying is nonsense. Avoiding a double free on a pointer can always be done with atomic reference counting so that only one thread claims ownership. That's the whole story. You haven't given a shred of evidence to explain what garbage collection enables something that was previously impossible.
It is obvious that if you had something you could say that directly applies to what you claimed before (some algorithms can't be done without garbage collection), that you would have already said it a long time ago.