[throwawayacc3]

There were multiple car lengths of room when the Tesla started merging. The other car was so far back it wasn't close to the blindspot. Americans do not adjust their speed or following distance to the conditions. They drive like they have some sort of right to a road free of obstructions and to drive at the speed limit or above, no matter the circumstances.

[rootusrootus]

Takes about 8 to 10 car lengths for an average car to stop from 60 mph, from the moment the brakes are activated fully. A fast human reaction time would be 150ms, but that's just to react, not to get the foot onto the brake. So add another 3 car lengths.

There were not 11-13 car lengths between the car in the left lane and the Tesla when it brake checked them.

Generalizing about Americans is tiresome, by the way. It makes you look petty and ignorant. Which might be true, but on the off chance you didn't intend to come across that way...