The difference is that when I go to my regular trainer, he is very specific about not letting me exceed my physical limits. He's also very conscientious about making sure I know my physical limits so I don't hurt myself when he's not around.
In a yoga class, the instructor can regularly instruct people to do things that are inherently dangerous (even if they aren't painful.)
Pushing the risk onto the students is not particularly helpful. The student has placed (or misplaced, depending) their trust in the instructor not to hurt them. It's the instructors job to make sure they don't get hurt, including not having them do inherently dangerous things.
You'd be surprised how much science understands about how the body works.
In a yoga class, the instructor can regularly instruct people to do things that are inherently dangerous (even if they aren't painful.)
Pushing the risk onto the students is not particularly helpful. The student has placed (or misplaced, depending) their trust in the instructor not to hurt them. It's the instructors job to make sure they don't get hurt, including not having them do inherently dangerous things.
You'd be surprised how much science understands about how the body works.