It won't be rare in driver code.

I’ve written bare metal code for rust that does networking and had only a handful of `unsafe` usages, and none after startup/init was completed. It’s actually really incredible how far “simple” shared-read-vs-exclusive-write bound checking and a very strict (but capable/likely Turing complete) type system can take you.

It absolutely will, particularly in USB code. USB devices other than host controllers don't have memory mapped registers for instance, it's basically a network protocol.