Regarding commuting via bicycle: it's not necessarily a problem with traffic, as more with weather. Also it's wrong to compare a single city, Amsterdam, with a bunch of American cities because of drastically different weather patterns in those cities.
Amsterdam has average temps (in F) from the mid 30's to the mid 60's[0]. That's prime bike weather. That's pretty much in line with San Francisco, which is a good city for biking. Even Manhattan and Brooklyn have reasonably overall pleasant weather for biking.
But compare SF to somewhere like Washington, DC, or Austin, TX. For 3-4 months of the year, DC feels like a swamp. Same with Austin. It's much more preferable to use public transit or drive than bike in that weather.
While the weather may be comparable, San Francisco is a very hilly city. I imagine that Amsterdam is relatively flat. In spite of its problematic, yet aesthetically pleasing topology, there is a strong culture of biking in SF.
Sure, the US climate is diverse, and it makes sense to use the appropriate transportation method for that climate. That doesn't negate the fact that "just keep using cars" is a bad idea.
Amsterdam has average temps (in F) from the mid 30's to the mid 60's[0]. That's prime bike weather. That's pretty much in line with San Francisco, which is a good city for biking. Even Manhattan and Brooklyn have reasonably overall pleasant weather for biking.
But compare SF to somewhere like Washington, DC, or Austin, TX. For 3-4 months of the year, DC feels like a swamp. Same with Austin. It's much more preferable to use public transit or drive than bike in that weather.
[0]http://www.holiday-weather.com/amsterdam/averages/