Comment It's been done. (Score 5, Informative) 226
In the late 1960s, I was taught high-school physics from the PSSC (Physical Science Study Committee) Physics textbook. The curriculum and textbook were put together by an NSF-convened panel. All the curriculum materials (textbook, supplementary readings, teacher's guides, experimental equipment) were made freely available. I still have two copies of the textbook produced by different publishers and with different covers but identical inside.
Although it was demonstrably superior to other physics curricula, the PSSC program was ultimately a failure because publishers, who couldn't make much money selling the PSSC textbook due to competition, eventually dropped the book and pushed hard to get their proprietary, therefore more heavily marked-up, textbooks adopted by school boards.