I am not so sure. In Germany, for example, the minimum required distance to the car in front of you is "speed in km/h divided by 2 in meters". So for 100 km/h, you are required to keep a minimum distance of 50 meters. I very much doubt that you can stop a car going 100 km/h within 50 meters.
The 50m is the reaction buffer, not the stopping buffer.
It’s also prudent to give more leeway to vehicles you can not see around to avoid the large truck swerving to avoid the refrigerator that just fell out of the truck in front of them problem.
You should be able to sing "Last night a DJ saved my live", which is a bit more than 2 seconds. I liked that, because it's one you can actually test for while driving.
I find it a lot harder to estimate 50m while driving at 100km/h
Not to disagree, just throwing in a variable that trains don't have