What is stopping American cities from changing their infrastructure investment from automobiles to micromobility? Is there one, big, standout reason that could be addressed? It's a change that takes decades and it's fighting against incumbents with deep pockets but it could be done.
Other than Manhattan, everywhere else a majority of residents own cars (Even in Manhattan I think it’s like 40% or something own a car). Moreover, the last 70 years of migration have led to a common pattern of people living in the suburbs and commuting via car to their workplace - replacing that with micromobility feels like a threat to their way of life and they will fight it vigorously.
What we actually see happen is even small tweaks like the 14th street bus lane in NYC get tied up in court and fought via democratic processes, when they do succeed it’s after a lot of effort.
Car ownership in the US has been steadily increasing over time. There's a small increase in "no-car households" since 2010, but it's around a .5% increase.
Walk? There is no place you can walk to from your house. Our strict zoning codes have carefully kept anyplace you might want to walk to farther from your house than walking distance. Even if we eliminated all codes today (ignoring all downsides) it will be many years before it makes much a difference.
Bike? Cities in the US are too large and spread out. You can get farther in a car than a bike. There is some opportunity, but not much because few people live within reasonable bike distance of work so they will have a car: once you have a car you may as well drive: you can fit more in the trunk than the bike racks, so it is easy to be lazy.
In addition, streets tend to wind around, you often spend far longer than desirable getting out of your neighborhood. This is only a few minutes by car, but on a bike it is a lot longer and you feel that when you spend a lot of time going the opposite direction of your destination because that is how the roads go. This is really hard to fix without knocking down houses. This same issue mean that transit cannot work, even if density is high enough (it typically is!) the winding roads mean the bus can't run fast enough to get people anywhere in a reasonable amount of time.
While you are at it, check the traffic deaths due to motor vehicles. Do it for urban environments, which is the original topic.
Oh, and the improvements in life expectancy for those who take regular exercise by, for instance, cycling to work. Better offset those. I suggest using micromorts.
