martine wrote: Personally I came to the conclusion many years ago (before the law) that . . .
What convinced me was helping a mate who, at the time, was doing a psychology PhD.
He was investigating possibilities for assessing the effect of brain injury on perception and driving ability. He needed a number of 'neuro-typicals' as his control group.
This particular task involved 'driving', on a laptop, through a simple environment of blocks. Along the way, there were things popping up on the screen which we had to react to. My typical reaction time was about 0.4s.
The next stage was to repeat the drive, also listen through headphones to a recorded sequence of random letters being read out. Then, as well as reacting to the on-screen tasks, react by saying 'yes' every time the audio said 'S'.
My reaction time dropped to 2s.
I wasn't planning on using a phone while driving anyway, but that clinched it.
Your 'standard' is how you drive alone, not how you drive during a test.