My experience in the Houston market is they do collude several ways. Sonic dealerships are centrally managed and secondly the managers do communicate between dealerships. They all want to hold the ADM's as long as possible. By agreeing to keep a certain ADM they essentially fix the market for a market area, it's especially easy for high demand low supply cars. Yes, there are exceptions, but it's pretty easy and obvious.
ADM’s don’t work if they aren’t paid. The market sets the price. If you’re mad that you couldn’t buy one before someone else willing to spend more, I get it, but it’s a pretty simple concept.
Sure, some dealers hang on for that ADM well past the buying craze, probably because they paid another dealer ADM to get it in the first place.