There's also the German church tax which is an extra 8-9% of your income tax. You have to formally leave the church rather than just stop showing up.
You nailed it. If one could give what they can when they can that is another story. What if you had a medical problem, your car was totaled, you needed a new roof on the house, etc. but the church automatically took money from increased taxes?
Here you could just make up the difference when your fortunes improved.
They desperately need a First Amendment, I don’t care if some inbred English nobleman calls it “bonkers”.