[Const-me]

> They are tools to make it easier to write correct code.

I agree with that. Still, being able to implement data structures without relying on unsafe features helps a lot with the correctness.

It’s possible to write code in safe Rust, but it’s hard to implement data structures in it. At least not if one wants performance. That rust’s borrow checker is simply too limiting for them. All basic data structures like linked lists, trees, graphs, LRU caches, use tons of unsafe internally.

That’s not the case with Java or C#. These garbage-collected VMs are memory safe all the way down. It’s usually possible to implement arbitrarily complex data structures entirely in safe managed code with minimal performance penalty.

Even their standard libraries are made that way now. AFAIK that wasn’t always the case, older versions of .NET framework did more in C++ for performance reasons, but they improved performance of JIT over time, and gradually reworked the standard library to almost 100% managed code, probably for portability reasons. Vast majority of third-party libraries in their respective ecosystems don’t use unsafe either, e.g. many asp.net web hostings are configured to forbid any unsafe libraries from being loaded.