The UK taxes are, in all fairness, the simplest I have ever seen (and I've made a point of learning about and comparing several countries). You can use a calculator such as Listen To Taxman [0] and be within a 1% error margin from the reality.

Of course, there are always edge cases, and the government has deliberately made some areas a mess (case in point: contractors); but the base use case of standard salary is insanely simple. And, for our American friends, the NHS is included.

[0] https://listentotaxman.com/

Most salaried people tend not to even bother understanding it from what I have seen. Magic money arrives in their account and that’s it.

If I explain to the same people that I use a spreadsheet for all my daily transactions I am looked at like I’m some kind of weirdo.

Not really. At least in the US, the tax code is lobbied to be kept intentionally confusing so that TurboTax et al can continue to make a lot of money off doing it for you.

It's hard to make a man understand something that conflicts with his ideological preconception that the government must be ripping him off.

Sadly many countries have 0 education on this topic and it might not be straightforward to get hold on good information about the subject.