This confuses so many people - the Uk has a series of constitutions and a very strong and historical legal basis for rights. It’s not strictly codified in one purposely written document but it does exist. And it’s a mistake to say if there’s no constitution then you have no fundamental rights. The UKs system is a hodgepodge but so is having a written constitution that can be regularly amended or otherwise ignored.
The problem with that view is that when the "strong legal basis" is not codified, and codified in a way that nonspecialists can at least vaguely identify and understand, it gets a lot easier to get away with ignoring it. Which the UK has been going hog wild doing in the last 20 years or so.
I am not saying the US is better in practice. The bottom line is that authority worshippers will take whatever liberties they can get away with in any system.
I’m not really defending the system, just making the point about a form of constitution existing. Even if the things you mention were nailed down in a constitution, that constitution could be amended to undo them, same as every other form of law.