Nick Finnigan
What you or I believe about the driver is neither here nor there. And we were not, AFAICS, discussing what should happen in some perfect world run by perfect beings with a perfect state of knowledge. We were discussing what will-won't happen given the state of the evidence.
Even though in many situations the dice are loaded against the driver in a way they never are for criminals (with the rules of evidence turned on their head), for the offence of driving unaccompanied to be proved, there has to be positive evidence of not being accompanied; it is not up to the driver to prove that they were accompanied. Their best bet may well therefore be to say nowt and wait to see what others can say (and can prove).
I am not aware that there is a log to be kept of the names, addresses and licence numbers of accompanying drivers. The learner need not even know the name of the accompanying driver and certainly cannot be penalised for not remembering those details. That's the way it was when I was a learner. Things change (of course), but I don't think that one has.