Those who run the gunshows could have stopped this before it even began, by making it unallowed to make sales at gunshows which do not go through a vendor for at least a state background check. I was at the Kingsporrt show this past weekend, where CNN purchased three pistols and one AR without any ID or checks, paying cash and walking away with the weapons. If the show organizers stopped the ‘non-vendor’ no checks sales in the show and immediate area, the ‘loophole’ would have been controlled at the state level. But then the organizers would not sell as many booths ... more than half of the gun booths in the Kingsport show were not FFL dealers.
They have always also been places for non-licensees to go and buy and sell guns for their personal collections, particularly in pre-internet days.
If vendors are buying and selling guns at gun shows as a business, they are already breaking Federal law if they don't have a license.