From talking to Brits, I'm starting to think that the greater availability of alternatives to driving one's self home seems to increase drinking. The need to get home, to get one's car home, is a good reason not to drink. During university I rode a motorcycle to school/work and can say it kept me away from many an afternoon at a beer garden. London's nightlife, the serious drinking, can only exist because nobody has to drive themselves home.

So dropping Uber into a city, giving them another option for getting home, might increase the overall level of drinking. This would muddy the drink-driving numbers. For every drunk driven safely home by Uber there may be some other person out there pressured into having a drink that otherwise wouldn't. And some of them might drive.