Pretty much a combination of everything that has been mentioned. One thing hard to measure is how much people just don't care about driving safely. They just want to get where they are going as fast as they can and screw everybody else. It doesn't take pot, alcohol, phones or anything else to make people just not care.
This. It blows my mind the dumb shit I see on a daily basis.
Example : There will be two lanes turning left, the car on the INSIDE lane will then immediately try to make a right turn, so they have to stop traffic to merge into another lane, then another lane, to make a right. Instead of just being in the ****ing right lane to start with.
Hurrr durr driving is hard.