Because ultimately - the government will have the last say.
It's any governing powers wet dream to be able to know everything about its people, that way - they can know what buttons to press, what feelings to arouse, people to use and abuse - because, lets face it - if YOU...the normal guy on the streets should get some of your little secrets exposed, they have you locked in...and you would NEVER revolt, because you STILL count your little secrets and "safe" life not worth sacrificing as your only reward for sticking it to the man...would be being hung out to dry and your life destroyed.
Well, how is that different from war? War have casualties too, but there is no honor in death. If you're still alive to fix things, there is hope - and without hope, we're truly doomed.
What if you have no secrets? I asked a few people if they would have a problem with the gov. storing everything about them, what they say over the phone, what they write, what they purchase - and maybe even their little secrets at home. The answer I got from most of them, was: I don't have anything to hide, I'm so boring, let them watch, let them know.
Say, I'm going to let you in on a little secret of mine, I know a lot about people too (use your imagination here, because you won't get some long explanation on that, call it LIFE experiences if you wish). In fact, I know so much about people...that I understand the lure of power, but I've chosen not to use it at all, but alas...most people would use it in a heartbeat, why? Because I've seen that too, again and again - as I stood by and let them abuse me with the knowledge they had, it could be simple things like buying new hardware for the company to better support the workers (which is BAD if you go against the company policy), but very good for overall efficiency etc. I've seen countless people abuse power - because they want SO badly to RISE in their ranks, make their small insignificant lives a little better for them and their families, at the cost of others...not in their family.
Have you ever seen the movie a Bugs Life? Not far away from how the governing elite controls the small everyday working ant...and like it that way, because lets face it, wouldn't you if you where given that option? To never have to worry about anything...ever again? To have endless purchasing powers? To always be right - even though you're completely wrong?
The moral of the above is, if you GIVE them this kind of power, they will take it - and you will only have yourself to blame.