Unfortunately, the incentives are quite different. In France and Germany, once you get a university research position or CNRS appointment, or in Germany a permanent professorship, you can essentially do what you want within the 36hrs/wk, and writing a nice little handout is what professors often like to do.

In the US, new faculty are judged by their research output and grant input and are still under the threat of losing their job if they don't make tenure after a few years. There is zero incentive to write a book on top of the 80hrs/wk that are put into the job already.

Also, in Germany, a university will absolutely buy textbooks in bulk for students to use, but that's a philosophical decision of how you want to run a society: if it's upheld as important that everyone can get (essentially) free access to top education, that's what you get. If education is treated like a business, you get something else.