Libraries off Github literally have the source available for you and the community at large to vet. And you'll find almost no sane shop on the planet where people are allowed, hell encouraged to use shady distros or install random utility tools in production the way they are encouraged to pull unchecked binary blobs from Docker Hub in an often non-reproducible manner.
Well, for most libraries used in Desktop Linux, a significant number of stakeholders (developers+users) exist, which actually care for development and the complete thing itself. Also the libraries generally are designed for solving problems and not getting github-stars by bots/dependency-building.
For docker (and npm for all that matters) _a lot_ of important dependencies are basically simple one-off "developments" with a single developer and no userbase at all caring for them, because they don't really solve any consistent problem, being basically just created to increase the visibility of its creator on primitive metrics. The community is there for high-level packages, but the dependencies lurk in test-scripts and seldom-used functions carefully placed by some idiotic digital nomads for their personal CV-polishment (ehm, not looking at you: https://github.com/sindresorhus/shebang-regex). Have a look at where this package is used (basically only in cross-spawn, where there are 10 other similar dependencies), then think about, how much effort creating the dependency hierarchy was, then look up who contributed the changes, where this micro-package was required and finally decide whether this was some thing sane people would do or if it's just for personal gain...
> Libraries off Github literally have the source available for you and the community at large to vet.
If Github was compromised, it would be easy and obvious to insert malicious code in a repository, but hide those changes from anyone on the github website.
