But can you average 60 miles per hour in your commute? Maybe if you're going 30 miles on the freeway and only a few blocks on surface streets, but for going short distances within cities, bikes can be comparable or even faster than cars (see: Bike messengers)
To be honest, I probably average more like 50. 3 blocks from my house to the road, then high speed almost all the way and 1 block off the main road to work. It's an easy drive.
You're right, the average American commute favors cars much more strongly. At 10 miles I'm remarkably close to my work and have a favorable biking environment most of the route. Yet it still is a bad alternative and in 7 years I have yet to see a single person bike along that route.
The question of "why don't Americans bike to work more" is not going to be solved with any number of bike routes (which I support the building more of BTW) until it can be solved for frankly trivial cases like mine. It suggests that local environmental conditions are probably more important to favoring biking than any number of infrastructure initiatives. Simple things like "bad weather" and "showers at places of employment" and "places to store bikes so they won't get stolen during the day" probably have to solved en masse long before bike lanes become part of the discussion.
All the unused empty bike lanes in the world aren't going to kick start a biking revolution.
Actually, at 10 miles, you're about median for distance. It's what's in between your home and your work that's abnormal.
Most employed Americans live, work, or both inside highly urbanized environments where parts of their commute involve roads that you can't reliably do 20mph on, much less 60. Crowded roads and stoplights put a real crimp on speeds, and it can take 5-10 minutes to cover a mile -- if you're lucky.
"How fast can you travel through town by bike and car?
The average travelling speed in Copenhagen is 15.5 km/h for cyclists and 27 km/hour for cars. In places with green wave for cyclist the average speed is 20.72 km/h."
It seems like Copenhagen is an especially unfriendly car environment.
Another advantage for cyclists is "right on red". Even though it's illegal, a lot of people does it. Sometimes the car lane to turn right is packed and you have to wait several intervals for you to turn right, and the cyclists just pass by.
The roads are small, especially compared to the US. And there're just too many cars!
The average speed of cyclists in Copenhagen is under 10 miles per hour. Add in a couple long hills and you are at 6-8 times faster on any given day.