>In 1925, only half of homes in the US had electric lighting. None had air conditioning. Many would have had only steam boilers (which can function without electric pumps) fired by hand-shoveled coal. Most would have had no insulation. In 1940, half of homes had no indoor flush toilets and no hot running water.

This is true but can be a little bit misleading.

You would expect new homes built in 1925 or 1940 to have many more of these amenities than the average. (you can see the flush toilet in the Sears 1914 home).

For context, The average home in the US today was built ~45 years ago.

"In 1925, only half of homes in the US had electric lighting."

Surely if our goal was to compare prices of TVs over the past 20 years, and if we found that prices of TVs haven't changed, you cannot then claim 'well, old TVs were 720p and modern TVs are 4K, so actually the price of TVs dropped 4 times!'

Today we have all kinds of things that increase productivity: electric power tools, prebuilt parts, laser levels and measuring tools, CAD software, flooring that interlocks, expanding foam that's easilly applied from a spray can, drywall and dozens of things I never even heard of.