> You're ignoring the gorilla in the room. Why can't one live in a comparable manner today and bank the difference?

For two reasons.

1. They're illegal. You're not allowed to build a house to 1936 climate, safety, and fire codes with un-licensed labor. And boarding houses were effectively banned.

2. Market. Most people would rather live in a smaller apartment than 1936 style un-climate controlled death trap.

And the reasons are the same for cars. You legally can't sell a new 1936 car, and even if you could most people would rather drive an 10 year old civic.

> Why can't one live in a comparable manner today and bank the difference?

You can do this. Just move to a sparsely populated area and work remote. Rural and semi-rural areas are basically the "poor", lower productivity areas within any given country, if you can arbitrage the incomes difference via remote work you stand to gain quite a bit.