Government: You owe us money; it's called taxes.
Me: How much do I owe?
Government: You have to figure that out.
Me: I just pay what I want?
Government: Oh no, we know exactly how much you owe. But you have to guess that number too.
Me: What if I get it wrong?
Government: You go to prison.
@MostlyHarmless Move to Poland. The happy path, that would apply to vast majority of people, is that once a year you visit the government website and click a button confirming that they got all the sources of your income right and you are done. It takes like 10 minutes/year.