Comment by kimixa

The #1 thing for driving safely is being predictable. Too many people seem to think "driving safely" is mechanically being able to control your car on the road, but that's the easy part. The difficulty is there are other people on the road all taking their own independent actions.

On a US highway you can glance in the mirror and see a vehicle, and you can work on the assumption that it's not going (much) more than 65mph. Or see a gap and have a general idea of how long you know it will still be a gap. Having a massive variety in possible speeds harms that.

I think many people seem completely unaware about how fast a car at 110mph (for example) can appear. It's in the order of time it takes to check your blindspot and other mirror - there's a hard limit to how many directions you can be looking at one time after all. No amount of "Personal Driving Skills" or "Being More Aware" can help that if the timing is unlucky.