In the Netherlands, the average biking speed in Amsterdam is 14.9 km/h. "In the popular cycling regions Drenthe and Overijssel the average speed is highest: 15.8 km/h." - http://www.holland-cycling.com/blog/260-amsterdam-has-slowes... [1]
9 mph = 14.5 kph, so nearly 1/2 of the cyclists in Amsterdam cycle "awfully slow" by your scale. The point is, they do bike. Though the average trip length was a bit over 5km, not 24m.
[1] This was by 55,000 cyclists who voluntarily participated in National Bike Counting Week, so may not reflect the general population.
And if we're talking average American commutes, a lot of them involve routes where you might have only freeways between you and your destination.
It does not obviate the need to visit a gym.
He probably would also disagree about what's most straightforward. I recall him recommending running in the book because it doesn't require any special equipment or training, in contrast to cycling, weight lifting, swimming, calisthenics, etc.
To be clear, I do think strength training is important as you age to avoid sarcopenia. But I suspect that running or cycling would provide enough resistance to slow sarcopenia for your lower body, making other exercise more important for your upper body and core.
https://www.webmd.com/fitness-exercise/features/no-gym-requi...
Edit: For the downvoters, this is not a controversial summary. Start with e.g. https://www.smithsonianmag.com/history/how-federal-governmen... https://en.wikipedia.org/wiki/White_flight https://en.wikipedia.org/wiki/Residential_segregation_in_the... https://en.wikipedia.org/wiki/Exclusionary_zoning
There are ways we can start changing it though: change the zoning laws, change the tax laws, etc. Changes to the built infrastructure will slowly respond over the coming decades.
Hell, my dad was only a telephone lineman for Ma' Bell, and he could afford 5 acres of land and a house in (our city's version of) the burbs.
Regardless of future changes to zoning laws, not everybody wants to live in big cities. There's a strong appeal to live in a house of your own, where your children can play in the grass with their house pet. Where they can go to school with a class size where they have a chance to actually know everybody in their class.
If you really want to increase the density of cities even more, people will either require a) no choice but to move to the big cities, or b) a fundamental shift in thinking about owning their homes and raising their families.
And please remember that you will be working against eons of human nature when attempting to create that fundamental shift.
Kids in a denser neighborhood with easy access to public transit have much better quality of life on average. Parents who move to the suburbs for the benefit of their children might just be projecting their own desires.
As for “aeons of human nature”: for most of prehistory and then most of history, most people were either living in isolated tribes in the forest, or as rural peasant farmers. Not sure how either of those is relevant to considering parking requirements, building height limits, etc.
There’s no inherent reason for class sizes to be different between urban and suburban schools. Often suburban schools have more resources because the USA spends more money on public services in cities with wealthier residents. That’s unjust public policy, but nothing directly related to population density.
Lots of people just like having a little privacy and a domain of their own.
Billings is the largest city and has only 160k people. Billings is spread out along a federally funded interstate highway, and has plenty of available land. It’s a place with harsh winters that would be rather unfriendly to pedestrians/cyclists anyway. 95% of households own a car, and on average there are about 2 cars per household. (For contrast, in NYC there are about 0.6 cars per household.) As far as I can tell buses are the only public transit in town.
Even today, some of those mining towns are bigger melting pots of various races, religions, and cultures than the port cities.
And with no money maintain it. Also with an "infrastructure of corruption" that soaks up whatever money is spent to change the situation. America has painted itself into a bad corner today.
The big problem the USA has is that its zoning laws and urban planning are completely screwed up, making it impossible in most places to build bike- and pedestrian-friendly neighborhoods. (Minimum lot sizes, low units per lot, low height limits, large setbacks, wide streets, massive numbers of car parking spaces required everywhere, few mixed-use areas, neighborhoods cut off by highways, lots of disconnected dead-end streets, very high urban speed limits, ...)
When I had a city commute (in SF), I was doing around 12mph average to get downtown, and biking was faster than the train (driving wasn't an option due to parking availability, both at home and work).
When I had a longer bike commute mostly on bike trails, I averaged 15mph at a moderate pace - I could go faster if I pushed harder.
Hills used to be an issue for a bike commute, they could really kill your average speed, but with the advent of electric bikes, hills are much less of an issue - electric assist can get you over the hill quickly and without much effort.
http://www.nyc.gov/html/dot/downloads/pdf/mobility-report-20...
A bus will be 4-6 mph, a taxi at great expense averages 8-9 mph. Sure, if you're not doing all 15 miles in city center but come in from outside, you can do moderately better than that, but for connections inside the city taking a bike is already the fastest transportation, even if you can only do 9 mph (and most people, in a flat city like NY, can do a lot more).