"What I’m describing is a classic market failure: people who are willing to do business together can’t make it happen. If taxis and passengers only knew how to find each other, and could strike deals that would appeal to both, everyone would be better off. Why can’t we fix this? As it turns out, a small but rapidly growing business is trying. One Friday night in December, my husband and I drove over to Adams Morgan for some karaoke with friends. 'You drove?' a friend who lives near us asked incredulously. 'I just used Uber.'"