Bike lanes and bikes aren't alternatives to most of what motorized transport is providing.
30% of the US can’t drive, whether because of disability, age, financial hardship, immigration status, or any number of other reasons. Why don't you hold the current system of "motorized transport" to the same impossible standard of solving all transportation needs as you expect of bikes?
Because your groceries are delivered by truck. Your houses are built with materials delivered by truck. In fact your entire lifestyle and the existence of the services which support those people, is provisioned and delivered by local road transport.
At least 80% of urban car trips could be replaced since the invention of the e-cargo bike. That doesn’t mean it works everywhere, of course, but there are millions and millions of people driving a single digit number of miles, usually at slower than bicycle doors-to-door speeds, and are never carrying 3+ kids and hundreds of pounds of cargo.
Think roads, not cars.
I am. Most of our road costs are for suburban car commuters and for subsidized car storage. If it was business usage and transit we’d need far fewer lanes, especially since businesses would use rail transportation more if the roads weren’t so heavily subsidized.
Most car trips are very short, and commuting to a CBD is easily served by transit.
Most middle-class people, especially parents of small children, aren't going straight back and forth between home and work. They're making other stops for day care, school, shopping, after-school activities, gym, etc. Often there are tight time constraints which make public transit unusable. Like it would be impossible to use transit to pick my daughter up from school and get her to practice on time. It's a constant juggle and the childless young urbanites who dominate HN seem to be ignorant of how regular people live.
I find it so weird that people constantly speak as though public transport is this hypothetical maybe like a moon base or something. I use exclusively public transport, bikes, and walking. My whole family (with children) does. It's just not a problem.
Children walk or cycle to and from school. By themselves. When they're very young their parents did go and pick them up sure, but then its a small school within walking distance.
We rented a car and a trailer for a couple hours recently to move a double bed. It posed no problem, and was dramatically cheaper than owning a car for a month would be even if the car itself was free.
I got a nice cabinet for my friend recently. We are going to take the drawers out and move it to his place on a bus. I don't think it would fit in your car.
Replacing most of car traffic in a city with public transport (and bikes and such) is possible, and it can work - after it stabilizes. The transition seems extremely disruptive, which might be why people speak of it as if it couldn't work.
I'm a parent with small children. We have a car, but we only use it for inter-city commute. Everything within city bounds, we handle by public transit or walking (or electric scooters). It works because we live close to the kindergarten, and close to multiple public transit hubs, and I work remotely. It works, because we planned for it in advance.
Now, take a typical car-commuting, office-working parent of today. Like most, the place they live in is frozen in some balance between their and their spouses' jobs. Changing it would upend someone's schedule, and possibly involve kids changing schools/neighbourhoods (which isn't good for them). At that stage in life, one's combination of home, workplace, kids schools and after-school activities, is pretty much frozen in place. If they made it work with car commute, it probably can't work with public transit, and thus if you suggest the change, they'll look at you as if you came from Mars or something.
That still doesn't solve last mile supply of stores and offices, nor does it solve construction, policing, emergency services, etc.
Each of those likely has possible alternatives to motorized transport, but they're all different alternatives. Meanwhile, today, they all share the same road network with regular civilian commute, sharing costs and mutually improving efficiency.
Put differently: instead of imagining all passenger cars replaced by bikes, imagine all roads replaced by bike lanes, then extrapolate from that.