I like your example... I've done the same, but it's important to remember that lots of those trapped people came from far away places on freeways that may not have access to a train... certainly that's true of the delivery trucks, which also couldn't deliver on a bicycle.

The key really is to move the marginal traffic that can switch. The key thing I see reducing cars is the absence of parking. Being at your destination, but unable to park (within a few blocks) is often enough to convince people not to drive.