When we arrived at the Yosemite gate on a Thursday at 11:00 am the campground sign said all sites full. This is an usually busy year and I think that what has previously considered the norm for first come first serve campgrounds just does not apply this year. In previous years I have arrived on a Sunday for first come first serve in Bridalveil and Tuolomne by 11:00 and haven't had a problem, but this year is an exception. We had people trolling the North Pines campground trying to take empty spaces because they were out of luck in the rest of the park. Problem with this (like I told the trollers) is that they are paid and reserved and people can and have arrived at their campsites in the evening and even at night. They paid for it and are entitled to show up at any time. I saw campers arrive in the middle of the night this year (very quiet and considerate though).
The trollers couldn't comprehend empty campsites sitting there while they become more and more desperate for a place to set up. Of course I directed them to the campground office as well as the camp hosts. Perhaps they were hoping that I would invite them to stay with us!
I also noticed Camp 4 was full of regular campers with complete disregard for campground courtesy. It looked like a shantytown (more so than I have seen in the past) and appeared full of families and big groups. Coolers, bottles of soda and food were all over the place and not in bear boxes. Too many people breaking the rules and not enough rangers to enforce.
I was told that some mornings at Camp 4 there have been no openings and others just a few. And if this is a desired place to camp, each member including children must be in line. No holding places (so the signs and rangers say).
Personally, I would be in line as early as possible to ensure a site, even if it meant getting up at some ridiculous hour and driving through the night. But that is me and my two cents!