I'm not an expert on building codes but a large difference in North America is there is much more space in general when building new so I don't quite think the argument is valid. Americans simply want a lot more space. If a developer built smaller sized 3 or 4 bedroom apartments they would have trouble selling to the price point they want.
All those above are just few and general top-hierarchy of a forest of rules.
Yes, those are all important and good for you, BUT all that add up to the cost for the actual build.
The land itself that is to be developed has to go through a long line of expensive processes, tests and certifications. Investigations to ensure that there is no disturbing bird nesting areas, or too close to small streams that may have rare species.
Again, all that is good, but cost and will drive up the price of the final product.
I've a relative in construction, and he notes that margins are so small it doesn't make much sense for all that effort when there are other options.