NO cars, Charles? That's a bit optomistic, and not exactly practical.
I'm thinking of two problems - first, transportation of goods. Cars (more exactly, trucks) will still be needed to deliver goods to stores, restaurants, and such. Yes, they can be a total pain in the posterior - I've been to NYC, and Philly, and DC, I've seen what these monsters can do to traffic when they're parked in front making their deliveries - but consider, if the traffic were restricted to just those trucks, it would be a lot easier getting around them. It's the personal cars that are the real problem.
Problem #2 - what about the elderly, the infirm, those who cannot "walk anyplace in thirty minutes" because it takes them thirty minutes to travel what most of us take in just five? That's part of why I included the tram service in my Rehoboth plan. I see a lot of the elderly when I'm at work, many (not all) of them wonderfully nice people, but they aren't very mobile and they are very happy when I pack their bags to their specifications, to make it easier for them to carry their purchases. We should try to make life easier for them at all times - they should be able to enjoy their lives as much as possible.