Not to mention the fact that however unhappy they are, 99.99% of them would be even unhappier if the baby were taken back out of the picture in some way.
I think it may also have something to do with the fact that Germany has some of the best stay-at-home policies of any country in Europe. Aside from longer paid leave--and now a proposed policy to have the government pay additional benefits for staying home even longer--German women have the right to reclaim their jobs up to 3 years later (in the US and UK it's 1 year, and in the US there are loopholes about how they have to
hire you, but they don't have to guarantee the exact same position you used to have.)
I know it sounds counter-intuitive, but having such great benefits puts a lot of pressure on moms to stay home, when some of them may not want to. Here, if a woman wants to go back to work, people may think it's for a variety of reasons, including financial. Over there, if you go back to work right away, everyone knows there's no excuse for it except you like your job more than your baby, and the last thing new mothers need is emotional shaming. Of the mothers who do work part-time,
half say they wish they could work more hours.