The big safety wins from Rust for me are things like the type system disallowing iterator invalidation, the type system handling resource releases, iterators making bounds checks a lot more affordable, the shared immutable/unique mutable distinction, the ability to encode that something can't keep a value somewhere accidentally, type system enforced thread safety, and others in that category.

Why would I need a good understanding of C++ to consider these built-in facilities or the ones that just happen due to the type system as safer?