Ignoring Grpg for the moment as I don't know the history of it you're wrong about the business licenses. They are often for specific things e.g. street trading or selling alcohol. A sole trader for example can go three months without registering when they start up, and when they do register it's only with HMRC unless they do a specific trade that requires a license. Of course this count for any trade where safety standards have to be followed and you have to be registered to work in the field (e.g. gas work).
This changes for every country of course.
Well I understand where you are coming from, and I don't know where you reside it's different for all of us.
For GRPG, if released under an open source license, you can't then sell it.