Why shouldn't the drink-drive limit be zero?!

because you are aloud to have one glass of wine then drive home. Even though you have a certain amount of toxins in your blood you arent completely intoxicated.

There are many things which contain alcohol. I think the limit should be lower, but should never be zero. Interestingly enough, there are a few countries which have zero tolerance.

http://www.ias.org.uk/resources/factshee…

Because Most people can have a drink or 2 before being to intoxicated to drive.
I think the question you should be asking is why are we aloud to text, girls do there make up and nails, and talk on the cell phone while driving. I lost a friend cause someone was texting while driving and didn't see the stop sign, the drivers blood alcohol level was .02 and he was clearly sober and not spaced out.

One drink with dinner does not impair most adults. If it does impair them, the cop has discretion to cite them for a DUI even if they are under the limit. I don't see the issue.

It would make things a lot easier I suppose, but then again some cough medicine or even breath spray & dental mouthwash have alcohol in them.
Even so it should be a bit easier than it is now.

probably just being realistic about human nature.... if it was, they'd be no space in our jails