My question is very simple: how to get rid of proprietary software from the Ubuntu Software Center (USC)?
It doesn’t work to enable or disable repositories. Even with just the “universe” and “main” repositories active you can still see plenty of proprietary software. Examples include Skype, Slack, Spotiffy.
Tested: Ubuntu 18.04 and Ubuntu 16.04.
Edited: I had to edit this question down to exclude another bug that I previously reported here about how many open source apps in the USC are mislabeled as proprietary. Added that here https://askubuntu.com/questions/1052688/open-source-software-mislabeled-in-ubuntu-software-center-usc-as-proprietary
UPDATE: This question remains unanswered and I believe it is a very important topic so it needs more attention. If Ubuntu claims to be Free and Open Source then give me the freedom to remove the proprietary software from your official Software Center please. Newcomers to Ubuntu Operating System will not know how to avoid the proprietary apps from the Software Center, especially since when they (I, and all of us) install Ubuntu we may choose only the Open Source repositories, yet the Software Center is full of proprietary apps.
UPDATE 2: 33% of the software is proprietary when you visit the USC home. Video https://www.youtube.com/watch?v=PIVHQj7pfXQ&feature=youtu.be Also Krita appears as proprietary and I reported here Krita labeled as proprietary in Ubuntu Software Center