Not so uncommon. While I was working in England, had an office mate, also American, who was a full blown alcoholic. The guy was drunk 24/7 including at work. Somehow, he wound up getting married to a British woman. Still a mystery? Anyway, he would stop at a pub on the way home every night to get blasted out of his mind. Obviously, the new wife did not like this.
We were about to go home for the night one day and he pulled me aside. He said, 'How can I get drunk on the way home without stopping at the pub?' I told him, 'Stop at a shop and pick up some beer, drink it on your way home.' He said the same as this guy. He said, 'That would be drinking and driving.' This is a guy who drove home bombed out of his mind every day of his life. But, he never drank actually in the automobile while driving.
In his mind, 'Drinking and Driving' meant exactly that. Anything else is perfectly legal.
