Perhaps the packagers on your platform went that extra mile to build binary packages. Taking a quick look, the Homebrew formula[0] for ripgrep on macOS just lists a dependency on Cargo (rust) and then seems to invoke the cargo command for installation. I'm not well versed in Ruby though, so my interpretation could be wrong.
I don't want to come off as entitled, either. I know the Homebrew folks are doing a ton of brilliant, ongoing work to make it work as well as it does, so I can't really blame them for potentially taking a shortcut here.
If it installs a bottle, then does it still require installing Rust? If so, then maybe that's a shortcoming of Homebrew.
Either way, it kinda seems like you're complaining about Homebrew here. Not Rust.
If having Cargo/Rust on your system is really a Hard No (...why?), then I guess find a package manager that only delivers whatever is necessary, or, if available, use the project's binary releases: https://github.com/BurntSushi/ripgrep/releases/tag/13.0.0
I don't want to come off as entitled, either. I know the Homebrew folks are doing a ton of brilliant, ongoing work to make it work as well as it does, so I can't really blame them for potentially taking a shortcut here.
[0] https://github.com/Homebrew/homebrew-core/blob/HEAD/Formula/...