It took 5 years to go from the creation of Nasa to a manned Mercury-Atlas.

We still haven't seen any of the space startups match a manned Mercury-Redsone, which took 3 years.

During the Mercury program Nasa was using on average 0.4% of the federal budget, which was little over 2 billion a year in 2020 dollars.

The big spending was on the Apollo missions which are pipe dreams for any of the current space startups 15 years after their foundation.

The safety culture and degree of acceptable risk is somewhat different now, from when we were sure we'd get nuked by the Russians in a month. (And also still thought smoking was healthy.)

You are comparing a different time in the US to now. I dont think this is a fair comparison, everything takes longer now -- buildings, bridges, tunnels. I'm amazed to hear how quickly subways in NYC were built -- these days it takes a decade to build a handful of stops.

I dont think it has to do with startups vs not.