> Well, legally speaking there's nothing standing in the way of charging for stuff incorporating GPL or BSD licenses.
It's not quite as clear cut as that. For one thing, FOSS usually includes bits which are not part of the code as such and not subject to a FOSS licence. The classic cases are artwork and goodwill.
> RedHat and Sony (and many others) have done pretty well out of that for decades.
RedHat sell support services and a bunch of value added offerings, as well as actually contributing in big or small ways to the code they ship, like many other distros. I don't know what Sony do but we all have commercial products that rely on FOSS to some degree these days, and that's fine.
What is being talked about here is people taking someone else's application, complete with original name, artwork, etc., uploading that to Microsoft (or Google or whoever else) and keeping any profits. And even so, the real issue is not the small amount of money they may make (although they tend to flood the shops with hundreds of ripped apps) but the negative impact on goodwill that the original developer takes, especially as it's not uncommon to add advertising and spyware to those apps.