Earlier quoted context omitted.
That is a very naive and idealistic position. Governments often and rightly have genuine reasons for keeping things secret - as do other institutions, businesses and indeed individual people.
Apart from "obvious" national security in the name of TERRORISM [1], what are such reasons? [1]: http://www.gwern.net/Terrorism%20is%20not%20about%20Terror
With respect to court documents: It could result is someone getting hurt or a mis-trial due to outside influences (ie. Rob Ford video)
There are obviously many reasons...