That’s why NC uses “Driving While Impaired” rather than drunk driving. You drink a couple of beers and pop a Benedryl and you still blow under the limit. But you are impaired
Or you take the time to dry out but by that time it’s late and you can’t see straight. There are tons of ways you can be in no shape to drive and blow a 0.000 on the machine, which is why most of the states changed their laws to deal with with non-alcohol related impairments, the cops got tired of pulling over bobbers and weavers only to find they were stoned not drunk and not be able to nail them with anything.