Mmm. True squeaky. I'm reserving judgement, but somehow it just feels wrong to me.
Motorway driving is different to regular driving. Higher speeds, people driving longer distances, tiredness, monotony. I can imagine quite a few people, in a nice pub-type atmosphere, might be tempted to have a drink.
The only way to judge the results is of course to build the pub and see if there's an increase in alcohol-related incidents on the M40 or surrounding area. I hope not.
But yes, I agree with you on some of your points.