The future has less power than expected. From the beginnings of the industrial revolution up to the first oil crisis, new energy sources were discovered, exploited, and scaled up. Space travel requires insanely high power levels, and it was assumed back in the 1950s that those were coming.
They weren't. In the last 50 years, there have been no new power sources.
We're still mostly on oil, coal, natural gas, and hydropower. Even solar cells and atomic power are now more than 50 years old. The existing technologies have improved, but there are no new ones.
That's why we don't have heated streets for snow melting, as seen in Disney's "The Magic Highway" (1958). We don't have much space travel because chemical rockets hit the power limits of chemistry around 45 years ago.
If controlled fusion is ever cracked, and it's not too expensive, we may see some of the older futuristic ideas back.