Re: compulsory education == compulsory profit.
I'm glad that you're so well off that you can afford to donate your time to the community for free. A lot of us aren't that lucky. We want to get paid for our hard work so that we can put food on the table and a roof over our heads. Do you really want to try to argue that teachers should teach for free? Why is it different for someone who writes software to help the teachers?
And what benefit does OSS offer to students who are only going to consume the content on the platform? The textbooks are just as open as they were when they were physically printed. Shouldn't the students get high quality materials that help and encourage them to learn, rather than whichever one fits your philosophy?
The downvote button's below for people who don't understand the limits of OSS.