I think that the space shuttle is really a re-usable second stage, albeit one which is firing its engines for the entire ascent. The aerodynamic demands on a r

I think that the space shuttle is really a re-usable second stage, albeit one which is firing its engines for the entire ascent. The aerodynamic demands on a reusable second stage are much greater, so comparing the space shuttle to the Falcon 1st stage isn't exactly fair. The Falcon 1st stage is more analogous to the Solid Rocket Boosters, in that it's a very high-thrust, high-density launch vehicle. The Solid Rocket Boosters are strictly speaking doing exactly what the Falcon 9 booster is doing: being recoverable. However, the Falcon 9 boosters have much greater capability to be re-used without refurbishment, since they don't encounter salt water.