This short post is in addition to the previous one about long term relationship between tutors and students https://www.indiehackers.com/post/would-somebody-be-willing-to-provide-long-term-real-teaching-6e7a6bd8dd
I have a feeling I cracked finally what's going on. There are 2 types of tutors/courses:
In the first case, all you need are videos/text and some way to show them. But in the second case, it's not as easy. You need to really teach students what means interacting with them, giving feedback, checking homework, answering questions.
I also checked Circles mentioned in the comments in the primary post. I found the community platform quite interesting but it's still hard to integrate into the learning process.