It is sometimes easier just not to drink and drive. It always tastes better when you cannot have more. Probably mind games, but annoying, and a temptation. Its a good point, though. It might well catch a few out, where as it is the serial offenders who are really worrying. They will not moderate their habit. Sadly a trip to the pub is now a special occasion for me. I used to be in 5 days of a week when I was younger.
Of course with all the useless gadgets on cars these days, a breath test starter might be a good idea. I guess folk would gib at a blood test including DNA so you car cannot be nicked. Big Brother.