I almost died on a freeway when my Subaru Outback decided there was something in front and engaged full braking.
110 kmh to 40 before it realized it was wrong.
pure luck nobody was following too close.
110 kmh to 40 before it realized it was wrong.
pure luck nobody was following too close.
Which is to say, in practice cars will be following too closely whenever there is high traffic volume, and systems that don't work under real life conditions are broken.
There are very few roads in my experience where long stretches are filled with high speed cars. The places that are filled with cars are usually around accidents and road works where the speed and hence separation distance are reduced.
I don't think a three second separation has any meaningful impact on throughput. perhaps someone with the necessary expertise and tools could simulate it.
Don't brake check on a highway. Also, semi-trucks exist.