So volunteers commit their time for free to create an open source software and when it is mature enough, big corporation comes in, repackages it and sells it?
Seems like a way to avoid dealing with those pesky things like employees, salaries, employment law and other regulation and just completely focus on seeking profit!
Those corporations of course have enough money to ensure politicians won't work on closing that loophole.
Another problem is that to work on these open source projects, you need to have a lot of free time, which means you are likely from a privileged background. Then if you have these projects in your CV you are likely get a job over someone who doesn't. This puts people from poorer families at disadvantage.
That's why we no longer allow volunteering at for profit organisations, because these places where snapped up by youth with wealthy parents.