Reference counting is a form of GC.

https://words.steveklabnik.com/borrow-checking-escape-analys...

Rust doesn't do runtime garbage collection. It "garbage collects" at compile time, in a highly optimized way, the same way a human would by manually writing "free". My understanding is that Rust does this well enough that there isn't really a performance cost compared to C.

Edit: I see your other comment about the use of Arc and Rc in the stdlib, that is a good point. However, how much does that actually matter? I'm genuinely curious, my guess is that it is not significant, but I'm not well informed. For example, would that affect embedded use cases?