Well, IMHO if at a festival there are seats arranged towards the front of the marquee and and people are allowed to stand in between them and the stage, I simply cross the festival off the list. There are still plenty of others to try.

I remember a Saul canal weekend where the family joined others sitting on the grass (no seats)about 2 feet away from the front barrier and still the ignorant people came and stood up to the barrier in front of us.
Yes i did ask them to move and they suggested I stood up.

Al