Good question. I doubt they do it when you land in China or in Russia!

it started with Institutional paranoia and is now an method to prevent critics of gouvernment to get into the us

because they are scary, tyrannical and totalitarian...

Our government is tyrant.

Genuinely asking – is it just because I live in the UK and am used just used to having a tyrannical government, or are people in the US overreacting a bit about this?

In the UK our terror legislation give our border police the power to question and search you without any reason or suspicion (regardless of nationality). Furthermore, you have no right to silence during this questioning and must answer their questions truthfully. You also must give them access to your devices, and if you don't you will face criminal charges

I disagree with this (obviously), but I genuinely thought this was a fairly standard among Western countries?

It's interesting because in the UK we have this view that the US is a backwards country in many ways, but then I see posts like this about what seems to me as a Brit to be fairly minor abuses of government power and wonder if I'm actually living in a totalitarian country without realising it?

Here in the UK we'd argue that the government needs this power to keep us safe. Some will disagree with this, but I'd argue that the people the government target at the border seem to be political dissidents and it seems that UK police are basically given intel by the state to question certain political activists under terror law whenever they travel back and forth from the UK.

The problem is it's hard to defend these people because they their politically extreme, but often very clearly not a terror threat.

This has become such a problem for political activists in the UK that it's become routine for them to take burner phones whenever they travel to prevent UK police attempting to search through their personal documents and conversations or charging them under terror legislation if they refuse.

More recently the UK government has shifted strategies a bit and now if you're a foreign national you're quite likely to just be refused entry. For example, we've banned people like Kanye West from entry to the UK for this political views (despite him apologising) which resulted in the music festival he was booked for being cancelled.

I know it may seem bad to people in the US, but you will get used to this. Like in the UK, US political activists will just learn how to protect themselves from these kinds of searches.

Not trying to minimise anyones worries or anything though. I hope you guys are able to push back against this creeping totalitarianism.