Isn't NASA famous for pursuing space entrepreneurs' ideas and thereby competing against them?

Some examples:

*Space stations: privatized Mir was doing more with less until NASA thwarted it:

http://www.spaceprojects.com/Mir

*Space tourism: shuttle flights for private passengers were heavily discussed as soon as Dennis Tito and Mark Shuttleworth showed that NASA was becoming increasingly unnecessary;

*The KC-135 Vomet Comet (I've been told that private entrepreneurs wanted to do something like this only for NASA to steal their thunder, and of course at taxpayers' expense. I gather, though, that this project IS being pursued and implemented privately nowadays though);

If NASA wasn't so jealous of competitors from a genuinely entrepreneurial (as opposed to mere contract-seeking) private industry, it would offer competitive prizes:

http://www.spaceprojects.com/prizes