" 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.
Quite. I have had LAPL(A) and LAPL(H) ever since they first came out and cannot see why more people don't take the same route. If like me you just want to fly day VFR in the UK (and Europe for that matter) it is ideal. The medical is also much simpler and lasts longer at my age. The freedom from the entire revalidation hassle is worth it on its own.