That's correct and that's the point: the bad scrum situation is sometimes in place because the TL does not do it all, either because they don't want to or is no

That's correct and that's the point: the bad scrum situation is sometimes in place because the TL does not do it all, either because they don't want to or is not able to. Sometimes, it is because the owners or the managements do not let them to. Sometimes, it is because when the owners or the managements gave them more opportunities, the engineering TL did not use these opportunities and the owners or the management had to fill the gap. As you said, taking these responsibilities is difficult for the TL and is asking a lot, so I don't think it's fair to expect it to be done systematically. On the other hand, on my own experience, it is not very difficult to understand the technical aspect. It does not mean "being able to code", it just means "the devs explained the situation and I understood it". My experience being in the middle is that devs are usually worst at understanding the business side than the business side at understanding devs. So I really think that it's unfair to say there is only two ways: either the TL take everything in charge and the decisions are good or they don't and the decisions are bad because non-devs are obviously idiots.