Now there's a statement backed up with fact.
You simply can't say that as even if one person goes on to change their habit or leave the car at home that one time because a relative/friend/colleague got detected and banned, then it's a potential life saver, maybe even their own.
Sorry I disagree. In the moment where there's temptation, I believe that no-one thinks "hang on a mo, I won't have that. I might get nicked and shown up in the local rag". Simply doesn't happen and so in my opinion the chances of causing a DD remain the same