People have been running different levels of privileged code together on the same machine ever since the invention of virtual machines. We have lots of lightweight sandboxing technologies that could be used when invoking a particular action such as tj-actions/changed-files that only gives it the permissions it needs.
You may do a "docker build" in a pipeline which does need root access and network access, but when you publish a package on pypi, you certainly don't need root access and you also don't need access to the entire internet, just the pypi API endpoint(s) necessary for publishing.
You may do a "docker build" in a pipeline which does need root access and network access, but when you publish a package on pypi, you certainly don't need root access and you also don't need access to the entire internet, just the pypi API endpoint(s) necessary for publishing.