> Everyone loves developing something for free and letting others benefit, right?
Sure! You don't have to look far:
https://drive.google.com/file/d/1KH7nh6M4QKW6KTKCudIX69eSR8YAE6BY/view
> 2) Who is going to maintain the question bank? Well, questions never need fixing, right?
Looks like you're not familiar with the distributed versioning model, for example the Git workflow most of the system administrators use to maintain Moodle code. For examples, see
https://moodle.org/mod/forum/discuss.php?d=459630#p1847324.
> 3) Whoever uses the question bank should still verify that every question is correct before using it. Right?
Of course. As the teacher it is your responsibility, and the privilege, to transfer only right things to your pupils.
> 4) How do you know that the questions were not created from copyrighted material?
One has to differentiate between two types of uses: a) in a closed group, say in your class. Then
fair use gives lot of freedom. b) Things you put on the (public) Web. Then check the copyright the author claims. It works smoothly under
CC licenses.
> How do you verify that every question is "original?"
Personally, I don't know how much of what I teach or taught are "original". I always thought the hard subjects like mathematics, science and engineering are repeating what "all" (except our students) know.
> 5) Where are these public question banks hosted? Is someone going to host the questions for free?
Again, you are thinking in terms of central repositories. The distributed model doesn't need any hosting. A Git repository is just a directory tree. I can have mine, you can have yours. Usually, one forked from the other. If we want to adapt each others modifications, the Git workflow allows to do that in a granular way. These "hosting" services like GitHub are just that, added services.
> Of course, the issues that I mention might all be resolved in one way or another.
That the point I mentioned at the beginning. These are not solved universally. Each individual has his own solutions for some or not for the others.
Pl. note that I've replied to the questions/statements to which I have an answer or something to say. I left out the others.
> Incidentally, if you are creating questions from scratch, I suggest using Moodle. Moodle provides great tools for developing questions.
Exactly! That was what meant by "questions" in the subject "Looking for collections of high school math + phys + cs questions". Which I later explicitly formulated as "a) Moodle quiz questions in the core question types, Formulas, STACK, CodeRunner and VPL", and then relaxed. See
https://moodle.org/mod/forum/discuss.php?d=459630#p1847752.