Utah has the worst system
All the sites said no reservation, first come first served, but they were all reserved with no campers. Camp host, as usual, nowhere in sight. I've camped in 43 states for decades and Utah is easily the worst state to camp at due to this system of theirs.
Also the drive up there is about 6 miles of winding hell with idiot children driving so fast I'm surprised there's not a death every day.