I'm kinda surprised how many people treat the tarps so seriously. I'm normally with 2-4 people, so maybe it's more of an issue with large groups, but I've never had a problem using someone else's tarp. Ask politely, don't be super loud, or encroach too much on the space, and you're usually met with friendliness.
Welp let me tell you a story SON. I was new to this Fest my 4 friends said, "watch the tarp" and all went to get beer and snacks. It was a break between sets. Our tarp was up front and center and we slept in the rain in a puddle all night just to get THAT SPOT!
So as my friends had all given me the command WATCH THE TARP and I being the responsible gal that I am noticed everyone starting to move in on me and my tarp so many people
Feeling overwhelmed I laid down on the tarp diagonally to take up space.
Folks started walking over me.
It was hilarious.
I finally got up went to the bathroom got a drink and came back.
The tarp was still there and like someone had a huge squeegee and swiped them all away they were gone. Respectively to their own tarps. OK I got this next time. So funny. Watch the tarp. Right.