I chemist friend said this recently about a zero limit
"So how will you deal with someone who has a gut fermentation problem and doesn't know it? Or someone who does physical work in an environment containing other alcohols - there are many different types of alcohol, not merely those we humans consume for relaxation and pleasure. Or someone whose metabolic processes are far slower than yours such that they still have alcohol in their blood stream more than 48 hours after consuming half a glass of very weak wine: conversely, how do you deal with someone with a very fast metabolism who consumes a single glass of alcohol and has fully metabolised it well within an hour - like your hubby?
Draconian measures always bite back and cause suffering and injustice. Or, as lawyers are happy to remind us: hard cases make bad law.
Law and the way in which we regulate and manage our society are all about safe sensible achievable balances. Total bans on anything never work - see Prohibition in the USA - and trying to force them to work just makes extra bureaucracy and significant added problems, not least by creating opportunities for criminal behaviour.
Try asking police forces how many extra staff and road traffic monitoring vehicles and other equipment they'd need in order to effectively enforce a total ban on drink-driving. Then ask yourself if you want to live in a society in which every person leaving a pub club restaurant or wine bar gets stopped and breathalysed.
Changing laws doesn't make society change. We didn't start using seat belts decades ago because of changes to the law; we did so because people made changes to the way they thought about safe driving in ever-increasing levels of busy traffic; we as a nation started thinking that driving without a belt was uncool and stupid. It was the clunk-click ads which changed people's minds, and they did that many years after the law had changed. Just as the Christmas drink drive ads made it uncool to drink drive and seriously reduced the numbers of incidents many years after the law on drink driving were introduced. What makes society change is other people's thinking and attitudes, not laws. Laws aren't deterrents, laws don't change societies; they are prescriptions for what to do when things go awry.
You need to be aware that zero tolerance cannot be made to work, just as zero incidents of drink driving is also not achievable.