The CAA proberly don't care until something goes wrong.
Then they will be after you and the rules are written so they can bend them as they see fit.
What can the instructor do for you sitting on the ground that they can't do in the air?
Sod all, thats why we send you solo. In fact being on the end of a mic in the circuit is more supervison for the student than if I am sitting on the can in the flying school.
MJ