It isn't that simple. The most important thing about a city is the streets and blocks. Manhattan and Barcelona are good examples of cities that have been designed in a way that make them walkable and high density.
The only places where you get non-walkable streets and blocks are the ones where you restrict density dramatically. Most cities aren't designed by some individual planning out where the streets should go. They evolved. If you allow an existing city to increase its density dramatically, people start demanding the streets improve to meet their needs.
The more density that gets built, the harder it is to improve streets. Construction of the interstates, Haussman's remaking of Paris, etc were immensely destructive, even if they enabled much more legible and prosperous development afterwards.
In the West at least, basically every street and block was laid out by planners from the early 1800s until post WWII. After that it's much more done by large scale private land developers (e.g. Levittown, Irvine).
It is harder but I also find that a poor excuse for not improving streets and infrastructure because it can be done and the taxes scale faster than costs. But people and politicians are short sighted and rather kick that can down the road either to make them look good from good financials or to leave enough money on the table for a bit of corruption.