Humans are not machines and human drivers are not homogeneous and it is entirely unclear how long of the duration of this "warning time" needs to be in an infinite number of conditions.
That is what is called #HumanFactors considerations, in part.
But let us put the "human element" out-of-mind here.
I submit it is not necessary here.
Let's get back to the article - and, in particular, a statement by one of the legal experts cited within it: