Economy of scale and tech maturity play heavily into that as its really no different than what modern commercial aircraft go through. The difference being that with modern aircraft we have a lot more practical experience regarding what does and does not work for a practical aircraft; along with a much larger economy of scale when it comes to spreading out research, maintenance and production costs. Now the shuttle was a white elephant, plain and simple, and never really delivered on what it was promised but many people forget it was also pretty much the first operational prototype for an entirely new type of vehicle and who's own origins date back to the late 60's. The fact that it delivered anything useful is nothing short of remarkable and on par with the original Write flyer being useful for more then a short hop. Government and private sector agencies are both tools in the same box, each have situations they are better suited for and one does not invalidate the other by mere existence. No more then a hammer invalidates a screwdriver. So an agency whose mandate is to perform pure science and initial research is not a case where the demand for profit at the end of each quarter at all costs is a good thing.