The German law/rule that blew my mind is known as "Abgeschlossene Ausbildung." What it means is that one cannot just change careers. One has to go through a formal program of study to change careers. I learned about it because I used to hang out on a lutherie forum. A really talented German luthier could not call himself a luthier in Germany because he was self-taught. PRS Guitars would have never gotten off of the ground if the U.S. had a similar career-limiting law.
Something to consider (not a defense of the system):
Education is almost free in Germany. Changing careers is a cost for those who don't go to College. It's an efficient system.
Won't get into the history, but nowadays the Ausbildung system is a buffer against uncontrolled immigration. A citizen of any EU country can work in Germany, but they need to learn German and do the Ausbildung, limiting the number of non-college immigrants.
Taxes are very low if you compare the perks that you get vs. the US. Health insurance, paid job retraining if you lose your job among others.
Not sure about not changing careers. It is correct for college vs. non-college; you cannot change paths, and not everyone can go to college (related to grades).