Droopy - you're quite correct
However, the emphasis here is that if you KNOWINGLY drive when you're feeling shattered, you're committing an offence (which, has probably always been the case anyway, but........ )
and therefore I feel that there really isn't any difference in flying an aeroplane or, chatting up some sad bint on the net all night, in that, if you crash after you KNEW you were unfit to drive - you might now face something worse than a wake-me-up-cuppa in the plods car!"
That's all, but I see your point