" can't understand why the (very experienced) instructor ..."
Nor me. Instructors are wonderful people, but like the rest of us make mistakes.
The rules are not the problem.
Complexity and confusion comes from what the rules aren't, from what senior people like this imagine them to be.
LAPL holders have a wonderful system, no examiners, no paperwork, responsibility rests on the pilots shoulders, nowhere else, just as it should be.
You will understand why I do not support replacing this with something requiring examiners, paperwork, etc.