German's pay a lot of taxes. Living costs and rent are sky high in cities. In the past, I reduced my hours to 28 hours a week because the difference was negligible in taxes paid. I even got money from the government to pay rent because my wage was lower.
There is a real problem where between salary band's, the money after taxes does not change significantly even if you're paid more. Working half a day only is incredibly popular for these reasons (among others). It's gone so far that politicans from all sides are publicly thinking about erasing the possibility for halftime work.