As Mel Gibson Says - FREEDOM! - what freedom?

I don't know why the Government wants to listen to all our calls and check out and monitor all our internet activities - If you ask them, they say its something to do with security and fighting terrorism. But in reality, if a terrorist wanted to avoid being caught by the Government, they just need to go to the £1 Shop and buy a few new SIM Cards - and give a list of these numbers to your Terrorist Friends with a code, telling them on what day to use which SIM - And if you are feeling generous, you can buy your friends some SIM Cards as well and even top these up with a Tenners worth of calls..  So the question remain, why the Government wants to listen to all our calls and check out and monitor all our internet activities?