spending that the private sector would not take on... 
  The Internet would never...private telephone companies 
  (dial up) would never...SpaceX would not...only something 
  like a national government

Note your continual use of "only" and "never". You made this a black and white question. I'll freely admit that the government can build infrastructure; you should admit that history shows that independent individuals can as well. Then the question returns to the relative cost-efficiency of each provider, which was my original point. And that's an empirical question: could these services be rendered for less than $5.62 trillion in taxes per year?