These are tiny programs.
I mean, sort has put on some weight over the years, sure. But if it were packaged up for npm people would call it a micro-library and tell you to just copy it into your own code.
Some of them are incredibly trivial. I made this exact same comment months ago, but the yes command is basically a one line bash function [1]:
function yes { while true; do echo "${1:-y}"; done }
For the comparison to be valid you would have to split up coreutils into roughly 100 individual repositories and replace many of the implementations with ones that are trivial, buggy, and/or unmaintained that pose a supply chain attack risk because it gets hard to keep track of what's maintained, by whom and how. Coreutils is close to 100kLOC and its programs aren't packaged individually. It is far, far from the random mess that are microlibraries in NPM.
less (17kLOC), awk (43kLOC) and grep (4kLOC) are separate projects, but some of those require a bit more insight than much application code these days, so it makes sense that they are individual projects.
You could paraphrase that as: core utilities that ship with my operating system should obviously be more reliable than random code fetched from the internet.
> For the comparison to be valid
I was responding to the limited scope of your statement "Yet, they are still a lot bigger than most micro-libraries. And more complex." Utilities like `yes` and `true` are neither big nor complex. The man pages are longer than the source code necessary to replace them.