To answer the question that is the title of your post, me dino comes hither with a response he wishes to humbly submit.
People who get behind the wheel of a car will oft posit their brains into a singular body cavity known by some (and other things by most others) as the anal orifice.

This a.m. Woman is behind car that stops for stop sign. She was in a hurry and switched over to another lane without slowing down. She hit a little 8 year old girl the other car was allowing to walk across the street (with the stop sign). She didn't even stop. (Great picture of her and the car) Her name is known everywhere it went viral on Facebook! But then, the town 'leaders' remarked 'no one stops for that stop sign!' They showed numerous cars running it. Did it ever occur to them to put blinking red lights on that stop sign (Solar). I've seen this in other towns! And at least put a stop sign in that other lane! Duh!

They put their brains in the "Glove" Compartment!

My home is between two schools. A young teacher was 'text messaging' and crashed through my cedar board fence ($800 damage). Fortunately no one was hurt. Students walk up and down my sidewalk daily.

Some funny examples...

https://www.bing.com/videos/search?q=...

I witnessed an incident many years ago when living in PA.

We lived in a Valley and driving to the City meant crossing a hill, with the two-way road presenting several sharp turns. A very low speed limit of 15 miles was posted just before you reached the hill. No passing allowed.

I was driving there one day just about entering the turns when a blue Mazda (never forget the color) came up behind me, zooming down at three times the speed limit, passing me. First thought flashing through my mind was how is this car going to negotiate the turn?

Barely finished my thought, when I saw the break lights coming up as the car went into fishtailing. By then it was obvious, the driver was in deep trouble, unable to control the car. Sure enough, after a few more uncontrolled jerking movement, the car flipped over twice, landing on its top.

I was right behind it, stopped and opened its door. There was a young woman inside, holding her head.

Luckily, she was not hurt but the whole thing could have ended in a disaster, hitting other cars.

A great number of people put their brains in neutral rather than their car. This will eventually end in a very bad situation for the driver.
A frinds son was explaining to his father what happened to cause the accident. I quote "Suddenly I looked up anthe th car in front of me appeared and stopped faster than I could". Son was 25/
I could give other examples but you get my oint. People just con't pay attention to what is going on around them even while driving a 3000 pound battering ram.