Worked in this area for a couple of years. We have automated collision avoidance systems and have for years. But things can go off nominal fast and you don't want passenger aircraft making drastic maneuvers that fast. Because conditions can change so fast, queueing theory isn't that useful either. It's useful for more strategic as opposed to tactical air traffic control, what we call air traffic flow management. There's been a ton of research in this area for decades, for example at the National Center of Excellence in Aviation Operations Research (NEXTOR) and at NASA's Aviation Systems division. I could say a lot more offline about why, in my humble opinion, progress has been unbelievably slow, but the short answer is that it's government plus modern day academia operating in an environment where funding is low and risk tolerance is lower.