To me, what would be interesting about a world without cars (or even with cars, but vastly more attractive public transport) is that it would partly reverse a sad isolationist trend that's come along with the power and control given to us by modern technology.

I used to catch a bus every day through the city, and there were a lot of strange people on those trips. Gangs of 9 year old gangster kids drunk up the back. Little old ladies muttering racist slurs at asian students. A guy who hadn't showered in so long his clothes had gone partially transparent from the grease. I don't think I was ever in any danger, but it sure was uncomfortable sometimes. I work pretty close to home now (in fact, mostly at home), so it's not really an issue anymore. But strangely, I find myself missing that chance to interact with people who I didn't choose to interact with.

It seems like every time we get more power (like by inventing an engine that can move us around) we use it to get more control (now I can encase myself in a metal shield that prevents any accidental congress with the outside world).

A bunch of technology has gone the same way. Efficient worldwide shipping and postage means you don't need to go outside to shop. Communication moving online means you can block people you don't like rather than have to deal with them. OKCupid means you can pre-screen your dates to avoid accidentally meeting someone unpalatable. You can GPS track your kids so they won't ever end up lost or at the wrong sort of party.

And those are all good things that give you more control over your environment. But they also isolate you. Unknown experiences are fundamentally scary; so scary that we feel more afraid of walking in a dark alley than we do of heart disease. Like every generation before us, we strike out against danger with the power of our tools. But our dangers are, at this point, largely invented. We're getting to a point where instead of being safe, we'll just be cocooned in a real-world filter bubble, where we never have to fear the unknown, uncontrollable, unsanitised real world that gets forced on us when we get on a bus or walk around a city. I suspect, for all our newfound safety, we'll just feel a bit unsatisfied.

I guess I've just argued myself out of believing that the future without cars is ever really going to happen. Maybe there'll be a virtual bus MMO.