I think the decision to pre-filter was based on the fact that kicking someone out was extremely difficult. Police had to be involved or some really bad thing had to happen. So the approach "ok we let anyone in, these are the rules, if you don't respect them you are out" is for sure more fair but it just wouldn't work. Theory vs Reality. And when you have 2000 people in a tight space you kind of want to avoid these situations.

I have no statistics but we can safely assume that 30 years of experience have taught the camping managers what works and what doesn't. I think it was in their right to decide who comes in and who doesn't.

I'm Italian and if you won't let me into your crystal shop because I wave too much my hands when I talk and you're afraid I'll break something (I personally don't wave hands), I'll understand. I will be angry sure, but not with you: with the other hand waving italians.