It wasn't a trick question. I'm not asking it in the same tone as someone would ask 'What can C do that Java can't?'.
I believe that Rust can be as low level as you want. If you have to fight the language to accomplish something, it's because you're probably trying to do something unsafe, and Rust will let you do that if you pay the price.
I was looking for examples of real cases where Zig is a better option than Rust. And while Zig is a lovely language, its main points against Rust are that it lets you do unsafe things more easily, and it's easier to learn.