Per sf comparisons blatantly ignore the bonkers increases in land prices. Good luck finding a 1500 sf house, let alone one with a backyard that hasn't completely outpaced inflation.
Land is not very expensive in most suburbs, but houses have become huge, the average size in the area where I live is 2700 sf. That’s because building a 3000 sf home doesn’t take twice the time and labor a 1500 sf takes, so there’s an economic incentive to build bigger homes. People also look for more space today than 40 years ago. A 1500 sf house would be considered a very small house and would likely be very hard to sell. Again, the average sf price remains in the low $200, so that’s not a huge difference to 40-50 years ago, factoring inflation. Not to mention you get much better quality materials, appliances and construction today. So, the fix appears to be more small homes, ideally condos, in urban areas just like many other countries do. The problem is, it is technically impossible to build multi family in most cities in America due to the ridiculous zoning laws and ordinances by city governments and neighborhood associations. If you own a lot in a city neighborhood and try to build an apartment building you will likely face years of court battles.