If every car trip really did mean sitting in a traffic for an hour, then I would love public transport more. Thankfully, that's not the case.
My wife and I take taxis a lot and, even in uber-dense HK, we rarely get stuck in traffic. When we do, it's usually just at a handful of choke points, like entrances to cross-harbor tunnels, and the traffic gets moving again once one is in the tunnel.
As to what one gives up by not owning a car, living in densely populated areas, and using public transport, I would refer you to an earlier reply: http://news.ycombinator.com/item?id=3974910
Basically, living close together and without a car means that the pain-in-the-neck factor of practically everything is increased. Everything becomes at best just a teensy bit more of a hassle and needs to be scheduled more carefully. Convenience and the ability to be spontaneous become more of a luxury.
If you're so certain that public transportation means giving something up, what is it that you're losing?