I know that it matters in Colorado. I was once camping and fishing with a bunch of the guys in my extended family up in the mountains, and on the day we packed up and left, we had a pretty bizzare accident.
I was in the passenger seat of the front vehicle, a chevy 1/2 ton towing a pop-up trailer. The next vehicle was a very loaded ford expedition, and the last vehicle was my brother and his friend in a jeep grand cherokee. We were coming down out of the mountians on a little two lane highway with a sharp rise on the right and a drop off into a river on the left. We get stuck behind some old fogey in a beat up old truck.
As we are driving along, I notice he appears to be slowing and see up ahead there is a driveway to the left where the river bansk away a bit. I then notice that I don't see any brake lights on the truck at all, and that my dad hasn't started reacting by slowing down. I start to mention something to my dad right as the guy in the truck decides he is going to stop and turn left, and he stops pretty suddenly in front of us, without brakes. I basically blurt it out "no brake lights, he's stopping to turn" as my dad jams the brakes, looking for an escape route. There is none.
One side of the highway is a sharp rocky rise with a gas wellhead pipe in the way, and the other is an oncoming 18 wheeler. As my dad jams the brakes and we screech to a stop and come within inches of hitting the truck in front of us only because he decides to pull up a bit more as the 18 wheeler comes past, my uncle, who has been taking a nap in the third seat sits up, sees the problem, looks behind us, and says "Here comes James!", and lays back down and assumes a crash position.
WHAM! We get hit from behind and lurch forward. The truck passes, and all four vehicles limp off the drive to the left, even the guy with no brakelights.
My uncle James in the middle driving the expedition had been too close and too loaded down to stop when we had slammed our brakes to avoid hitting the guy with no brake lights, and he had hit the trailer we were towing, which sheared off the hitch on the truck and shoved the tongue up under the rear of the truck. The grille, bumper and front hood of the expedition were toast, but it was driveable because the back end of the trailer had crushed and the front end had sheared off the receiver. The truck was driveable, but couldn't tow anymore.
The cops showed up and gave the guy with no brakelights a ticket for no brake lights, but then gave my uncle James a ticket for following too close. He told us if our chevy had so much as nudged the back of the guy's truck with no brake lights, then that guy would have gotten all the tickets given out that day, and consequently the insurances would have all blamed him. By avoiding that collision, we got my uncle a ticket. FWIW, he probably was too close considering we were going somewhat downhill and his vehicle was pretty loaded.
We ended up getting the trailer hitch replaced in town, and towing it back with the jeep, and all three vehicles made it home.
I was pretty pissed, as we were supposed to raft Royal Gorge on the way home, and the collision ended that.