Is the state of open source textbooks that bad? I guess the top link is a U of MN site, which is laudable and a Big10 school, but not exactly a banner carrier.
It saddens me that with github and the like, and the armies of wikipedia entries, there aren't open source textbooks of greater/higher quality than any of the publishers. I guess biology and some sciences deviate a lot edition to edition, but basic math? physics? chemistry? economics? history? languages?
Of course institutes of higher learning have well exposed themselves as being anything but in the last couple decades. So it doesn't really surprise me. The entire "open coursework" movement died quite quickly when the colleges realized this might cut into their annual 10% hike to tuition.
But like your father, I'm surprised some retired teachers don't do this as a side project, or an emeritus professor, or SOMEONE that wants to leave a legacy.
You could have a site that presents concepts in entirely different fashions, so you could choose a path that suits you, or if a particular concept didn't stick, have it presented a different way.
State institutions in particular should be required to produce and use open textbooks and courseware. Rile up some republicans to make it contingent on getting their state funding (they love doing that).
This is even more egregious since there is the entire British Commonwealth of nations/english speakers and their educational systems to leverage.