For a given abstraction, think API, the number of correct implementations in Rust, C++, C and Assembly is roughly the same, and it is much lower than the number of correct implementations in, say, Python. That's what "low abstraction" means. The abstraction can be very precise with a rich type system like Rust's, but that doesn't make it any wider. This means that clients are just as sensitive to changes in implementation details, and that the cost of maintenance is high relative to high-level languages, even though the type checker can find the mistakes and tell you that the considerable work you may have to do is not done.