> Space is inherently limited and replacing existing buildings with new more efficient ones is also problematic when you have people happily living in those old buildings, especially in high demand areas. Construction work takes time and in the meanwhile the displaced families will create even more demand.
The main reason old buildings with lots of people are replaced with somewhat taller new buildings, is because of bad laws that require new apartments to go only where old apartments already exist. IMO these are exactly the laws that need to be reformed and or abolished. It doesn’t mean that no one’s old apartment building will ever be demolished for a new one, but right now that’s effectively a requirement. If you want to add four space to a city, you are first required to demolish a large amount of apartment space, and evict everyone inside. If you could simply purchase a house that was already on the market, whose owners wanted to sell and didn’t want to live there anymore, and replace it with an apartment building he wouldn’t evict anyone. This transaction was once common place, but is now effectively illegal almost everywhere in North America because “house people” demand segregation from apartment people.
> There are practical limits on how densely you can pack floor space before it becomes prohibitively expensive, unsafe, or simply impractical. As you build higher the costs grow exponentially while the livable space per floor keeps decreasing due to the tapered shape of the building and need for larger structural core and more elevators. Above certain height you will be forced to target wealthier residents which means either offices or large luxury apartments that are anything but space efficient.
All true, but these limits are really only relevant or binding in Manhattan and perhaps one of two square miles worth of downtown cores in a few large cities. If someone wants to say that Manhattan will always be expensive for those reasons, that’s fine, but it’s no excuse for the other 99.99% of places people want to live in.
Reforming land use successfully IMO doesn’t require us to solve the problem of “how to make Manhattan (or places like Manhattan) even taller” but the much more economical goal of “it should be legal to build a 4 storey walk up with no parking, anywhere you can build a house.” That’s a tough political goal to be sure, but it doesn’t come close to having to deal with any sort of physical or efficiency limits regarding construction of very tall buildings.