We seem to be on the same page, but you are I think being biased by that perception and so assuming both that all GMs run their game that way, all game systems encourage that view point, and that all players prefer it. I don't believe that is the case.
It's possible to run this challenge you've described using a only flow chart which at every branching point features, "Character failed or succeeded?" and never branches on player choice at all, and I think some GMs lean very strongly to preferring that process of play. If I used such a flow chart, this would be entirely a character challenge, and even if it wasn't a pure character challenge because a few trivial decision points for the player remained, it would still be close enough to a pure character challenge that I wouldn't feel amiss calling it a "character challenge".
Some games, at least as written in the rule book, have a process of play where every player proposition ALWAYS is mapped to a particular rules proposition which calls for a fortune test, and for each proposition offered to the GM, the GM's role is to interpret correctly which rules proposition the player actually made. I've even read rule books where it called out that if the player made a natural language proposition, and it was unclear which rules proposition - which character 'move' - the player was making, that the GM should invalidate the natural language proposition and force the player to phrase the proposition as a rules proposition.