You agreed to a lot of stuff just by installing Linux and the userspace. Even the MIT license has a limitation of liability clause - if the maintainer published malicious code (like node-ipc on NPM that would nuke the computer if it had a Russian IP), you’d have a difficult time bringing that to court.
We just usually don’t care about it because it’s not as disruptive as a big corpo’s legal goatse, and FOSS maintainers tend to be better people than corporate lawyers.