While it may never be "enough" depending on your requirements (which you didn't specifically and coherently define), the amount of "review", and having the required know-how to do it competently, is much bigger/higher from your crate dependants, than from your distro packages.

It's not rare for a distro packager to not know much about the programming language (let a lone the specific code) of some packages they package. It's very rare for a packager to know much about the specific code of what they package (they may or may not have some level of familiarity with a handful of codebases).

So what you get is someone who pulls source packages (from the interwebs), possibly patching them (and possibly breaking them), compiling them, and giving you the binaries (libs/execs). With source distros, you don't have the compiling and binary package part. With crates.io, you don't have the middle man at all. Which is why the comparison was never right from the start. That's the pondering I left you to do on your own two comments ago.

Almost all sufficiently complex user-space software in your system right now has a lot of dependencies (vendored or packaged), you just don't think of them because they are not in your face, and/or because you are ambivalent to the realities of how distros work, and what distro developers/packagers actually do (described above). You can see for yourself with whatever the Debian equivalent is to pactree (from pcaman).

At least with cargo, you can have all your dependencies in their source form one command away from you (cargo vendor), so you can trivially inspect as much as you like/require. The only part that adds unknowns/complexities is crates that usebuild.rs. But just like unsafe{}, this factor is actually useful, because it tells you where you should look first with the biggest magnifying glass. And just like cargo itself, the streamlining of the process means there aren't thousands of ways/places in the build process to do something.

less likely to be insecure

Evidenced by?

requires reviewing all source code

This is exactly the la-la-land view of what distributors do I was dispelling with facts and reality checks. No one is reviewing all source code of anything, except for cases where a distro developer and an upstream member are the same person. And even then, this may not be the case depending on the upstream project, its size, and the distro developer's role within that project.

to make sure it meets interoperability

Doesn't mean anything other than "it builds" and "API is not broken" (e.g. withing the same .so version), and "seems to work".

These considerations happen to hardly exist with the good tooling provided by cargo.

and open-source standards.

Doesn't mean anything outside of licensing (for code and assets), and "seems to work".

Your argument that crates.io is a known organization therefore we should trust the packages distributed is undermined by your acknowledgement that crates.io does not produce any code. Instead we are relying on the individual crate developers, who can be as anonymous as they want.

Largely correct. But that was me comparing middle-man vs. middle-man. That is if crates.io operators can be described as middle-men, since their responsibilities (and consequently, attack vectors) are much smaller.

Barring organizational attacks from within, with crates.io, you have one presumably competent/knowledgable, possibly anonymous, source, and operators that don't do much. With a binary distro, you have that, AND another "middle-man" source, possibly anonymous, and with competence and applicable knowledge <= upstream (charitable), yet put in a position to decide what to do with what upstream provides, or rather, provided.. X years ago, if we are talking about the claimed "stable" release channel.

The middle man pulls sources from places like crates.io anyway. So applying trivial "logic"/"maths", it can't be "better", in the context being discussed.

Software doesn't get depended on out of thin air. You are either first in line directly depending on a library, and thus you would naturally at least make the minimum effort to make sure it's minimally "fit for purpose". Or you are an indirect dependant, and thus looking at your direct dependencies, and maybe "trusting" them with the "trickle down".

More processes, especially automated ones, are always welcome to help catch "stuff" early. But it is no surprise that the "success stories" concern crates with fat ZERO dependants.

Processes that help dependants share their knowledge about their dependencies (a la cargo vet) are unquestionably good additions. They sure trump the dogmatic blind faith in distros doing something they simply don't have the knowledge or resources to do, or the slightly less dogmatic faith in some library being "trustable" if packaged by X or XX distros, assuming at least someone knowledgable/competent must have given a thorough look (this has a rough equivalent in the number of dependants anyway).

This is all obvious, and doesn't take much thought from anyone active from the inside (upstreams or distros), instead of the surface "knowledge" that leaks, and possibly gets manipulated, in route to the outside.