I can provide a little personal insight into this situation. We went to pick up our son Sunday morning, before the huge crowds of people going to get the Missionaries returning from the Philippines, that was Sunday night. We called the airport ahead of time to see what the protocol was, they told us to stay in our cars on the second level of the temporary parking structure, and our son would be sent out to our car. Naturally, we assumed they had some sort of system in place to direct the kids from the baggage pick up out to the cars.
When we got there, we waited and looked around for some sort of airport employees to help us or tell us exactly how this was going to work, not a soul in sight. We waited until after his plane had landed, and still no one around to even talk to. It's not like we can just text our kid where we are parked, obviously they have no phones or anything on them. We had no choice but to go into the building and see what was going on, we walked all the way down to the baggage claim, still no airport employees anywhere. We had no choice but to wait by the baggage claim for him to come down. There were a few other parents and sibling there, maybe 50 people in total.
99% of the blame for the huge crowds Sunday night lays at the feet of the SLC airport, all it would take is a couple employees at the doors to the parking structure to take down names, or phone numbers, or even just slap a number on your windshield or something so the kids would have a way to find their ride home.
This was not a coordinated effort by hundreds or thousands of "Mormons" to break any law, just small groups of families there to pick up their kids, and the airport did absolutely nothing to have it be even somewhat organized.