I live in Utah now. I've driven in many countries and many states in the US, and by far and away the drivers here in Utah are just useless compared to most other places. They brake and slow down for the most inane things. Bends in the road, traffic cones, bridges over the road, green lights. Literally anything that isn't a dead straight line free of traffic and they'll brake. There's a section of motorway heading north out of the city here that is 5 lanes wide and even in the middle of the night there's a traffic jam there. The only reason is that the entire motorway does a long right-to-left 'S' bend with a slight hill in the middle. There's no on-ramps, no off-ramps, nobody merging, no changes in the HOV lane. Merely the presence of two bends and hill causes people's brake lights to come on. Just for reference, these are not tight bends. You could easily do that entire section of road at well over 100mph if it was empty and you wouldn't even notice it.
It's so bad that I've seen people brake and swerve for a shower of leaves coming off a tree and blowing into the road. People now regularly slow down to a near stop at green traffic lights. They don't know how to pass a cyclist without literally driving into oncoming traffic on the other side of the road. They have no concept of how wide their vehicles are so to pass a bus that has pulled over - well - for the most part they won't, they'll just sit there blocking traffic.
It's all down to one thing : in the US, a driving license is considered to be a right rather than a privilege, and as such it's made as easy as possible to get one. For example in Utah, the road test is 7 minutes in some suburban back street with no traffic, and the written test is a non-time-limited, open-book, multiple choice test. (although believe it or not people still can't pass it). Compare that to places like Sweden, Norway, England, Germany - any other country where driving is taken seriously - where it can cost a couple of thousand dollars and a nine month investment of time to get a driving license.
It's no surprise then that the accident rate in Utah is four times the US national average, and sixteen times the European average......