Just look at this shit:

https://github.com/rust-lang/rust/tree/master/library/core/src/slice/sort

There is unsafe all over the place in the source code in these folders, including giant blocks of unsafe as part of implementing algorithms.

Why does Rust force developers to learn the intricacies of unsafe and bear the maintenance burden of unsafe when they want to implement common algorithms like sorting algorithms efficiently?

The Rust standard library has had at least several occurrences of undefined behavior and memory unsafety, so don't tell me that unsafe is fine. https://materialize.com/blog/rust-concurrency-bug-unbounded-channels/