Sure, this doesn't work everywhere. But think of Los Angeles. Very high population density, apart from a few hills it's mostly flat and the climate is nice. To get to any place 1 mile away I'd have to go by car. Often there is congestion and I have to wait in traffic. Plus, there is no direct route to the place so have to go a huge detour - perhaps even shortly on a highway. This could be so much easier and healthier by bike - if the city was built for this.

Bottom-line: some cities can never be be great for bikes. But most can but just aren't.