It was a fairly common trope in "golden age" sci fi iirc, along with moving people roads, and people tubes (like the Futurama opening credits). Elon is straight

It was a fairly common trope in "golden age" sci fi iirc, along with moving people roads, and people tubes (like the Futurama opening credits). Elon is straight out of a Robert Heinlein book - the crazy billionaire building rocket ships to mars, he's even made them stainless steel so they shine like on the old astounding adventures covers. Edit: here's the roads must roll https://en.wikipedia.org/wiki/The_Roads_Must_Roll https://en.wikipedia.org/wiki/The_Roads_Must_Roll one of those ideas that sticks in your head