Not sure what you put in to get that number (keep in mind that $100k is roughly €92k) but there are many possible variables that can change your tax rate. In my personal case it is significantly lower than the number I posted above.

I used mostly default values in the first online calculators I found for both California & Germany in the example in my original post.

Just from personal experience: 42% is pretty much on the dot. It might be that with 92k you're still taxed in a lower class (or maybe you're married and thus getting a discount).

Yes, I chose the wrong tax class by mistake.

My personal tax rate is even lower than that as we have 2 kids & my wife and I file together (both self employed so we add up our incomes and file with all tax bracket at double the threshold). I think we ended up paying just over 15% off the top of my head but don't quote me on that (I earn less than €92k but still enough to have a very comfortable life).

I knew you pay more as a single/childless person but I didn't realize just how much more - which makes it all the more surprising that Germans have such a low rate of both marriage and reproduction.