I think this is a major issue as well. Adequate following distances give you a reasonable amount of time to stop should the car ahead of you slam on the brakes

I think this is a major issue as well. Adequate following distances give you a reasonable amount of time to stop should the car ahead of you slam on the brakes for any reason, it gives other cars the ability to seamlessly change lanes rather than slow down which causes traffic, and they cost you almost no time as you can create a following distance by dropping your speed to literally 1-2 MPH less than the guy in front of you for 30 seconds (and going that much slower for that little time can add less than a second to your trip time depending on your average speed). This all feels intuitive yet so many people on the road fail to keep a distance for no discernible reason. Is it that they think you're supposed to be close to the car ahead? Is it that they feel driving is a competition rather than a cooperative arrangement set up so that nobody crashes into anybody else?