There is an easy answer. Put a computer in charge of it (well, okay, we're all mostly software engineers and we all know it's not that easy - but - you get the point).
Aggressive driving and tailgating are bad because humans are not capable of making good choices at those distances/speeds. If you could 10x our reaction speed, then those actions would not be as looked down upon (going 6-8 over the speed limit is technically illegal most states, but nobody on the road is going to think you're some kind of maniac).
Simple little simulations like this teach us that simple little simulations do not account for reality and the complex nature of the meatbags in control of each vehicle. A more realistic simulator might be able to roll the dice that a driver might not notice an obstacle in time, and crash straight into it - putting more debris and obstacles on the road for every other driver to avoid/crash into[1]. The gains in net flow from have everyone drive like madmen would probably immediately be wiped out from the hour(s) spent getting emergency vehicles onto the scene, redirecting traffic, treating the driver, towing the vehicle, etc. Not to mention that there would almost certainly be multiple scenes down the road - as there usually already are during rush hour - and we already condone this type of behavior!
[1] https://en.wikipedia.org/wiki/Rubbernecking