Chronic weed usage changes the way you're high. The time distortion nearly goes away and you can control your attention pretty well. I'm not endorsing driving high of course.

From watching chronic weed smoking friends... I do not believe this. If anything, they're much worse and much scarier more dangerous while driving. They definitely should not ever drive high.

Isn't that because they're also thinking they're invincible and can handle it, so the weed usage does not actually cause their driving behavior? At least that's the case with my own acquintances who drive high. As I said, I also don't think it should be allowed to drive high, however the effect long term usage has on a person is genuine, albeit definitely not generalizable - I'm pretty sure the strain is an important factor.

From my own observations, it was more that their reaction times were much slowed down and their depth and distance perception affected. I know one guy who crashed into a object while high. Luckily he wasn’t driving fast and nobody got hurt.

By the way, the Czech police says "you can spot a high driver by how unusually carefully they drive".