The point is that the infrastructure investments required for public transports would be even higher, taking into account that roads are also required for public transports...

If I want a bus or a train to be right in front of my house any time I need one and I also want that bus/train to drive me exactly where I want to go, obviously the cost will be ridiculously high.

You set unreasonable expectations/ demands on public transport. There will always be some walking / biking to/from bus/tram stops. That has never been a problem.

You are likely trying to compare the USA car-centric suburbs and frankly that choice makes distances larger but that’s life. USA has a tremendous disadvantage due to the car-centric nature.

Yet even that can be changed, it will be costly, but there is no technical issue. It is all about politics. As long as taking a bus is seen as for “poor people” it will be an uphill battle.

I am in Europe and I am replying to a claim that public transport can be made so good that it is people's first choice... and so the point I am making is that this is indeed setting an unrealistic expectation on public transport!

If you need some biking or walking just to reach public transport, then wait, then travel through the network then there is always a level of inconvenience that you may not face if you use individual private transport instead.

Even in Europe most people live is suburbs. Even if they are not car-centric (and they are in most cases) that increases inconvenience and cost of public transport.

> that you may not face if you use individual private transport instead.

Only if you assume that individual private transport can get you door-to-door. Which is a rather unfair comparison. "cars are better because unlike public transport, you can drive up to basically any building and park there" is only true if you build roads and parkings to basically every building.

Streets have to access all buildings due to fire fighting reasons, unless you also plan to rearchitecture the firefighting infrastructure to use pipelines branching from a huge central fire extinction station.

Firefighting vehicle doesn't need parking space

It is obvious that a building requires road access. The issue of emergency services access has already been mentioned but there is also obviously the issue of deliveries, including large items like appliances and furniture.

I did mention the caveat that sometimes private transport (which includes bikes) may be inconvenient. That includes issues with parking space.

I'd argue that making private transport very impractical is not the same as making public transport "so good it becomes the first choice"... it's making private transport bad enough that it becomes more inconvenient than public transport...

I'm not so sure about that. The subsidies that a functioning public transport requires every year are massive as well. I wouldn't be surprised if they exceeded the cost of extra infrastructure (roads, parking etc.) required by private cars.

Public transport would obviously need much less space and would be much more efficient. It’s the car sprawl that is unsustainable in every way.

In a dense city centers? Probably. Everywhere else? I'm not so sure. An average person will is bothered by wait times longer than 10 minutes and wants the stop to be within 5-7 minutes from their door. So, you'd have to run a bus/tram every 10 minutes through a ton of sleepy suburbs, which may not even see a car every 10 minutes. It's just not rational.