Realistically, hysteria apart, the net result of this will be zero. If you are dumb enough to drink and drive, there are already gazillions of places that you can drink and then hop right onto a Motorway. Maybe we should close all those, as someone already said? Or bring back Prohibition?
By definition, the incident Red referred to (person driving the wrong way on a Motorway) can't have been due to drinking at, then exiting, a Service Area the wrong way, can it? (which, by the way, is probably quite a bit harder to do / less likely to happen, at a Services than at a normal junction?)