Why does a beauty therapist need to instruct the client on their positioning on the massage table?
Presumably this is because the client won’t automatically know what position to adopt on the massage table, just like when you are at the dentist for instance they tell you where to face, how wide to open your mouth on so on. You are the expert and you need to tell the client how to position themselves, and presumably if they are in the wrong position it could lead to damage to them or at least the massage not working or being as effective as it could be.