However, bonding out projects does spread the expenditure in time, more directly charging the future users for infrastructure they use. Sure you could recoup the costs through user fees, but then you're effectively borrowing money from the current tax base, so "bonds" by another name.
On the social side: the gamble is that social growth will outpace the increased economic pressure. Meaning, you need the new vertical growth to create opportunities faster than it increases prices further in the area. A land tax alone wouldn't pull people out of poverty, create affordable housing, or open up public school. Those are all just potential avenues for the city to develop, not guarantees.
On the environment: cities aren't isolated enclaves. Resources needed to build, maintain, and feed the city all come from the outside world. The more you build up the more steel, concrete, glass, energy, etc is needed. The more people packed into the city the more food you need to ship in and waste you need to ship out.
One million people would need about the same amount of food/energy if they lived in 1,000 sq. mi. as they would if they lived in 100 sq. mi. But the cost per person to house and transport people in a dense city is lower than in a sprawling one.
There are a lot of ill defined and bizarre things here. What is "economic pressure"? I have never heard such a term before. Why would there be "price increases" (inflation)? I have never heard anyone serious posit a link between density and inflation. It's the exact opposite because economics of scale and scope can deliver services more efficiently. Why shouldn't a land tax contribute towards "affordable housing" when the economic logic predicts it will have a deflationary impact on housing costs? Why do you think I'm saying that a land tax will "open up [new] public schools"? I said there would be a change in incentives away from excluding poor people from your local school catchment area, which has historically driven local resistance to upzoning. Honestly, it sounds like you should read up on basic economics before you form these opinions. The subject matter is primarily economics and such basic knowledge is a prerequisite to understanding the rationale behind one tax or another.
> The more you build up the more steel, concrete, glass, energy, etc is needed.
No, this is forgetting that you have the same number of people in either scenario. It takes more resources to build 1000 single detached homes (and associated roads, train stations, shops etc) than 10 apartment buildings with 100 homes (with less roads, less train stations than the former scenario).
Price increases are possible here because it all depends on what is built on the currently vacant lots, or on lots that are cleared when the old buildings no longer make economic sense with the new tax. The example given early in this thread was a car wash versus a new biotech facility. A new, expensive biotech facility wouldn't help with affordable house at all but it would bring in more individuals with higher salaries. Prices could also go up if new construction further increases the city's density or population - more people means more demand and higher prices unless supply increases faster.
Economies of scale aren't a given simply because a new land tax would change building incentives. Economies are much to complex for that and can't be boiled down to a single lever or knob. Changing one thing can have a much different outcome than predicted.
I'm not sure why you would expect a land value tax to have a deflationary impact on housing. There's no direct link between a land value tax and an increase in affordable housing, meaning we can't assume there will be more affordable housing created. What we do know is that land owners now have a new tax to pay, and if you are renting out property on the land you will pass a large portion of the new tax onto them in the form of rent increases. This is literally a concept covered in the intro to economics course I took 15 years ago, if you aren't aware of how businesses handle new taxes I'd recommend you read up on it before pushing too strongly for a new tax.
[1] https://www.smartcapitalmind.com/what-is-economic-pressure.h...
On the social side: In the current system, poor people are forced to live in ghettos and spend 2 hours a day on a round-trip commute. It's too expensive to live near their work. If we had a land tax, the rich enclaves near the city are now financially incentivized to open up their public schools and areas to poor people by building vertically. The current incentives at play make this extremely difficult.
On the environment side: We will have less sprawl, and by extension less environmental damage. It requires less concrete, less energy, less roads, less driving, less shops, less train lines, etc, to serve a dense area, on a per-capita basis. You are however correct that natural reserves are a public good, technically speaking, and an efficient land tax system will need to account for public goods in its implementation. This is an important implementation detail that I'd defer to economists.
Use the revenue from the tax to build infrastructure. Obviously it can't be an overnight thing, but we can do it over a decade-like time horizon.