Things were a lot less tense 20 years ago when games didn't sell in the five figures. There is too much cash involved now to be really casual about a show.
What it seems like is that the hobby has changed but the show runners haven't - they want people to bring their $5,000+ toys, leave them for three days to get the snot beat out of them, and want to fine them if they leave early.
How about, instead of punishing the people that make your show possible, you make it *attractive* to bring your games? Prizes - real ones, not $20 throwaway garbage. Real incentives to stay the whole day/weekend.
Remember, people who bring games are doing YOU a favour. Act like it.