You're SLOWLY getting there...
While Mr Mathieson has a long way to go, he is clearly beginning to understand what has been happening - and some of the commentators are way ahead of him. Which is heartening...
During the 1940s, we had a World War. In a war, the normal checks and controls that society expects to put on a government are thrown away. Your government may forcibly commandeer your property, attach you to the armed services, and investigate/spy on anything it likes.
Just after the war, many of the state bureaucracies which applied these new powers were swept away. Several were happy to be closed down - but many put up quite a fight. One example of the sort of thing that happened can be seen here:
Clarence Henry Willcock
Our State Secret Police and Intelligence Services were lucky - they survived the end of the war quite easily by moving into the Cold War virtually unchanged. Gradually the Cold War shrank, disappearing entirely in the early 1990s. It may be interesting to consider whether it would have gone earlier if it had not been in the interests of Security Service, the SIS, NSA, the CIA, KGB, Stasi, and many similar organisations to keep it going.
When the Cold War died these organisations were staring redundancy in the face. They have built up the threat of terrorism to justify their own existence. It may be interesting to consider whether Middle Eastern politics might have been very different if it were not for the intelligence services input encouraging destabilisation.
The intelligence services do not particularly WANT to spy on the entire civilian population. I'm sure that they are quite uninterested in the information they are gathering - indeed, they probably can't make any practical use of it. Famously, they have NEVER been able to show an example of a plot uncovered by the use of it. What they are interested in is justifying their existence. And big projects like this are self-perpetuating, and ideal for maintaining a lifetime's career.
We need supra-legal intelligence services in wartime. In peacetime we need the rule of law, applied by the police, democratically accountable and presented in open court. And that is what our intelligence services do not want to hear, and are very scared to see discussed...