Michele,
I agree - this would be discrimination in my opinion. To answer your original question, I can start your list by giving you several shows that I've participated in here in AZ that have had no such rules about commission artists. The Tubac show had no commission on top of the booth fee, but the Scottsdale shows required 5% of total sales. I had several sample pieces there that were for sale, but as expected, did not sell any of them.
The shows are:
http://www.tubacaz.com/festival.asp
http://www.888artfest.com/5thavefall/index.html
http://www.888artfest.com/scottsdale/index.html
This one I hope to participate in either this year or next:
http://www.thunderbirdartists.com/fe...festival.shtml