Exactly. The social and economic contexts are completely different.
With regard to labor costs... quite right. That $2300 in 1949, when adjusted for inflation, is less than $25k in 2018 dollars.
You raise another good point about the relocation of infrastructure. What about boring through forests, wetlands, etc. to lay track and power lines? And where's the power going to come from? Coal, natural gas? What about transmission losses (and issue which is often ignored).
So that signature plan sounds good when a politician says it quickly, but its cost-benefit fades on closer reflection.
As for requiring people on social assistance to do some kind of meaningful work in exchange for benefits, just imagine the uproar from civil libertarians and unionists!
You make a very good point wrt work ethic and sacrifice too. Imagine peoples reaction today to the JFK rhetoric (and that's what all political speeches are, after all, even the stirring ones like JFK's) about going to the moon!
https://er.jsc.nasa.gov/seh/ricetalk.htm