I admitted as much -- there is change. I would be quite historically wrong to say otherwise, which I didn't. I said 'rarely'. U.S. History has recorded more status quo upkeep than transformative change. And there has been more transformative change in matters of populism than in matters of the state, like security.
The appropriate time frame would be 238 years.
* It took 89 years for slavery to be outlawed.
* It took 144 years for women to have the right to vote.
Those are populist changes that occurred before our births (I'm assuming on your part, at least). ... The government will cave to popular demand if it is sufficiently strong enough, even pulling out of war, as was seen with the Vietnam War.
In terms of national security though, U.S. History records far more status quo than change. This is where 'rarely' really applies, as does the continuance of previously enacted policy. ... assassination of American citizens without due process of law (started by Bush 43) and also indefinite detention (also started by Bush 43).
Go back now to the Church Committee. President Ford went against the grain and discontinued and outlawed certain practices, like assassinations of world leaders, which President Carter followed. President Reagan, however, did not. Ford had also worked to curtail domestic spying done by the security services, though it never did stop, and it has been a part of the U.S. national security paradigm since before J. Edgar took over at the F.B.I. But every POTUS denies allegations of domestic spying. They have to. "Yes, we're spying on Americans..." isn't going to win hearts and minds here, for as President Kennedy said: "The very word "secrecy" is repugnant in a free and open society; and we are as a people inherently and historically opposed to secret societies, to secret oaths and to secret proceedings. We decided long ago that the dangers of excessive and unwarranted concealment of pertinent facts far outweighed the dangers which are cited to justify it. Even today, there is little value in opposing the threat of a closed society by imitating its arbitrary restrictions. Even today, there is little value in insuring the survival of our nation if our traditions do not survive with it. And there is very grave danger that an announced need for increased security will be seized upon by those anxious to expand its meaning to the very limits of official censorship and concealment."
But it happens and happened during his heyday nonetheless. It has too. There is too much money and power at stake for it not to.