If you look into building codes in North America, you'll find out that they were almost all decided by industry board rooms with no public engagement. You don't need a conspiracy to make every cheap and sturdy form of construction illegal, when the people that wrote the regulations were literally owners of Portland Concrete, several timber companies, and several "insulation" companies. You don't need a conspiracy when a group of rich people just acted in their own self interests.
We should be able to build adobe style homes that require almost nothing in the way of sellable construction materials, along with attached root cellars, and ice cellars. That would bring the cost of the average home down to $10,000-20,000, while eliminating the need for HVAC systems, as well as a refrigerator and freezer. Both of which have to use energy to function less well for food than engineering technologies that are hundreds of years old. A fridge can't keep an apple or orange at peak freshness for 6 months. A properly packed root cellar can, even in summer months. A freezer will create freezer burn eventually. A proper ice cellar won't, even during the dead of winter.