Affordable housing

I have previously pressed the case for inexpensive housing using prefabrication.
See:
http://www.kevilldavies.com/2010/10/affordable-housing.html
http://www.kevilldavies.com/2011/01/prefabs.html
http://www.kevilldavies.com/2013/08/emergency-housing.html
http://www.kevilldavies.com/2014/12/housing-costs-and-rule-of-two.html

Now, call me a cynic, but as politicians again ring their hands about the shortage of affordable housing, I feel that they they are to blame. With the answers so obvious, I can only conclude that the major political parties must be in collusion with the major house building companies to stop the use of cheaper alternatives. Can someone prove this?