It's like asking why does the king of Saudi Arabia need to have the power to jail his subjects for no reason? Why does Putin need to have the right to jail or kill political opponents?
The UK doesn't give you right to remain silent (your silence will be used against you), you are compelled to bear witness against yourself (you must surrender passwords), and there are super-injunctions where you are gagged and not even allowed to discuss the legal issue with your lawyer.
This is the country that sent government thugs to force journalists to physically destroy their own laptops and hard drives.
With religious clergy overtly and explicitly being part of government power (in house of lords).
Hell, it's super recent that government power in house of lords stopped being inherited.
Imagine if the US senate was staffed solely by inherited power. Not just in the style of Bust Sr/GWB, but actually inherited. It's not the same, since the US senate is more powerful than the house of lords, but "it's complicated".
So your confusion here may come from the fact that you look at the UK as "like the US, but they talk weird", where it's a couple of step closer to "Like Saudi Arabia, but part of political power is elected".
Obviously Saudi Arabia is much further away along this spectrum, but I hope you see my point anyway. You seem to be saying "how can a free society do this?", where the answer is "because it's not that free, your assumption is flawed".
But there's a difference. The US is not living up to its ideals of equality and democracy, or even equal treatement under the law (e.g. lying to congress about not "collecting" data about US citizens). The UK is not even aspiriting to living up to those standards.
For example take torture. The best way to paint this is to "do horrible things for the protection of freedom and democracy". It's Realpolitik.
I'm still absolutely against torture, but it's a difference in kind to the UK putting religious clergy into positions of government power.
It's possible to defend torture as an instrumental goal to the ultimate goal of freedom & democracy. But the UK is not aiming for the same ultimate goal.
Similarly it's a difference in kind when Trump or Bolsanaro practice nepotism, compared to when some asshat gets a peerage in the UK.
We can list flaws all day, but the difference between the US and the UK here is that the US really does have an ideal of equality, freedom, and democracy, and the UK does not. The UK has not outgrown the Monarchy. And I'm not just talking about the royal family, but the whole aristocracy.
Another way to explain this: If you tell the story of Plebgate to an American, they won't fully get it. It's an insult, yes, but merely saying it's an insult is missing the point. It's bad because the class society is still there. People owning their homes often still literally pay a land tax to someone with a lord title. A land Lord.
It's a step on the spectrum to Saudi Arabia, where within its borders every grain of sand, and every person, is the personal property of the king.
If you take the US and add a permanent unelected head of state, add 20 dedicated priest posts to the senate, remove the first, second, fourth, and fifth amendment, and on top of that have a society that generally feels like this is a good idea, then you have a completely different country.
And it's not a country that even aspires to be as free or democratic as the US. And since the UK doesn't try, it also isn't.
Under Trump we saw that the US institutions were (mostly) holding. What's being "held" in the UK is not even a goal on the level of the US.
You point out many things. And probably those kinds of things the US has done more than Saudi Arabia has done. But nobody would therefore conclude that Saudi Arabia is more freedom&democracy than the US, would they?
https://news.sky.com/story/sarah-everard-baroness-who-sugges...
This idiot (who is clearly making a completely idiotic contraproductive and divisive point, since I'm charitable enough to not take her at face value) is there for life. She can't even be voted out. She's there for life.
But what can you expect from the Green Party? Are they actually competent at what they do in any country?
She claimed some massive disability following an operation, and the hospital's own investigations team followed her and filmed her jogging, drinking, etc.
It would have been using these same powers to do the surveillance work.
If it's that serious, have them ask an intelligence agency to investigate and report - as they do anyway today. They don't need direct access.
But yes, crazy that the Food Standards Agency always end up on this list. Must be someone who knows someone.