It's an example of richer, expressive interfaces that allocate responsibility for who ensures what behavior properly for the problem. Send and Sync don't fundam

It's an example of richer, expressive interfaces that allocate responsibility for who ensures what behavior properly for the problem. Send and Sync don't fundamentally make thread safety easier. What they do is that library authors can provide abstractions to users and each side has a clear scope of diligence. Rust's realization through Send/Sync is more complicated in practice, demonstrated by that one bug for Mutex(Guard?) in the standard library, but pulls its weight well.