RE: No, no one else reads GDPR consents notices either!?

One of the biggest issues with taxation in the UK is it's deliberate over-complexity.

New tax regulations can come from Acts of Parliament, statutory instruments, HMRC regulations, and precedent from first and second tier tribunals. It's reckoned that the volume of new rules arrives faster than any single person could read them. Much of it is poorly written and full of loopholes.

It's also notable that HMRC's brief appears to have changed (without, as far as I know, any announcement) from "collect the correct amount of tax from each person" to "collect as much tax as possible".

If you are well connected and rich enough, you can get away with paying a lot less tax than the ordinary person !