Your stated concern was:
> You follow the instructions on Trisquel, and now DOZ is installed, and
listed in your applications list. Since everything worked flawlessly, you
assume DOZ is fine, because you just installed it using Trisquel.
Which suggests to me you don't understand the purpose of Trisquel's repo
policy. It comes from this part of GNU FSDG:
> All the documentation in a free system distribution... must take care not
to recommend nonfree software.
Because of the way something like Debian's repository works, it effectively
serves as a recommendation to install software in it. It's designed to help
you find software you might want. So a distribution like Trisquel needs to
have a different repository that only includes libre software (or no
repository at all, but that would be terribly inconvenient).
Note that this has absolutely nothing to do with how easy it is to install a
proprietary program. There's nothing wrong with including a facility which
allows users to install proprietary software easily. Take Wine, for example.
pip works similarly, but it has an important difference you're ignoring:
whereas Trisquel's repo is maintained by one person or group of people, pip
is just a place where anyone can upload Python software. It's more like
SourceForge, GitHub, or Savannah in that sense.
pip is also typically used for a completely different purpose: to install
Python packages you already know of which aren't available in your system's
repositories. I checked, and pip does have a basic search feature, but I
would say this is a borderline case at worst. After all, we don't say that
pointing users to search engines (like DuckDuckGo), which will happily show
you all kinds of proprietary software websites and advertisements, is
unacceptable.
> Shouldn't this be done as well in the case of pip?
No. That would be overkill. PyPI includes standard tags indicating licenses,
so all you need to do is check those tags and omit programs not listed as
under libre licenses from the search results.
But what should be done is completely different: just add a disclaimer to pip
saying that there are no guarantees about the integrity of software it
installs. Such a warning could be given when the pip install command is used.
I'm sure the maintainer of pip would be perfectly happy to accept such a
patch.