One of the things that comes to mind about why it is so hard to measure things in this industry is that almost nothing is commodified, and the commodities and s

One of the things that comes to mind about why it is so hard to measure things in this industry is that almost nothing is commodified, and the commodities and specifications are all at the component level, which vary wildly over time. If you want to measure the productivity of steel production over time, you can get a reliable measure of what the prices were in 1979 and what they are today. A "house" or a "building" is not a commodity, though. There are prefab structures which are more commodity-like, but they are the exception, not the rule. And then to top it all off, the costs of acquisition differ wildly depending upon where you are. Land values are hard to filter out in the reported data. Labor issues are different based on where you are. Etc. In the recreational vehicle industry, there are different classes of vehicles. Things are pretty standardized. You can get a rough sense of improvements or regressions over time, in terms of both price and quality. A class A vehicle is not the same as a class C vehicle. You can track fuel efficiency over time. And the factories are fixed in location, and there is no locational value to filter out. There is no such official classification system for homes. We have informal names for the various styles of homes, but they have no formalized meanings or reliable reporting. But in a world where prefab construction became commonplace, this may be another matter. And if construction took on this form, arguably the quality over time could improve. Why is automotive glass so much better than the glass we use in residential windows? Why is the attention to detail so much better in cars than in homes? I'm sure the annual tax penalty on buildings doesn't help... something vehicle owners don't have to deal with. And I'm sure the rampant speculation in land doesn't help either. Both could be improved by shifting taxes off of buildings and onto land. But of course, prefab construction is outright illegal in much of the US.