I don't have a lot of experience of US cities, but we were in LA for a while last year and getting anywhere without a car was a bit of a nightmare, the mere suggestion of walking gets most people looking at you as if you are completely insane. That's partially because of the sheer scale of the urban sprawl though, apart from a very small part of Downtown virtually everything is one or two stories high and everything has huge parking next to it, which means that the distances between any two points quickly become huge. Then there is the sheer volume of traffic and a lack of dedicated cycle lanes and riding a bike becomes a bit dodgy.
I think in general European cities are doing much better at this, they are more compact generally, and most are taking steps to reduce traffic. Places like Amsterdam and Copenhagen are in many ways more bike friendly than car friendly, have been for a huge period of time and it shows in the number of people who cycle there.
Others, like London are catching up as well. London started a 'congestion charge' for people driving into the centre of the city back in 2003, and has added increasingly charges and Ultra Low Emission Zones since then, and the decrease in traffic is really clear. At the same time, they have invested a lot in creating cycle lanes on existing roads and also dedicated cycle 'highways' across the city.
It's all very well telling people to get on a bike and ride to work, but it does have to be safe and easy, and cities have to invest in the infrastructure to make that possible.