Physics does not care for theory much.
Just because something has always been done a certain way does not make it correct. It used to be that wives did not have their own tax code, women could not vote and the colour of your skin, your race and the church you did or didn't believe in had a significant affect on which school, university, golf club, job etc you could attend or go to.
What we have now is what is called progress. We want legal accountability, happy insurance companies and safe flying. If we can have all this and then also make it fun well done us. On the flip side if we can have fun but cannot satisfy the above should we be doing it.
When the original legislation was drafted (probably alongside the King James version of the bible) Pontius was a pilot and there were not aircraft landing every 90 seconds at LHR.
I have been as a PPL, a CPL and an FI on flights in and around Farnborough, Blackbushe, High Wycombe and Biggin Hill and surrounding London I have also flown 737s into LHR when incursions occur from all of these directions. I understand both sides and their needs but when I have an A346 in front of me and a B773 90 secs behind me I really do need to know that the solo student on his 1st X-Ctry nav has the perspective and training in his head of the consequences of me going around with limited fuel at the end of a 7hr sector, causing someone else to go around or worse having to follow a TCAS RA in this sort of airspace.
Now you are likely the sort of instructor whose students do know this but you are not the garden variety PPL with PPL only knowledge type of chap are you.
I have taught at schools where senior instructors (DCFI & CFI) advise students to turn off their transponders so that they don't get the school in trouble if they make a pesky zone incursion (in the above mentioned areas) This is a very unlikely trait for a CPL/ATPL holder to perpetuate
I agree the CPL question bank is out of date, nowhere near as relevant as it should be and can suggest far far better ways of doing the exams but this does not change my view that you should teach the level below you and that only CPL and above should instruct anything ever.
It may be a fun day out for the chap who hired the PA18 from Booker or the chap doing aeros in his Pitts from Biggin, it may be a great bit of fun for the Red letter day winner on the 'trial lesson' from Shoreham but it is the end or start of a long day for those doing 220kts on base, 180kts on final or 250 kts on departure separated from each other by often no more than 20 seconds.
We are all in the same airspace so no I agree that a 300hr PPL likely has have specific light aircraft knowledge that puts him ahead of a integrated fATPL straight of the FI course. But isn't that why we have restricted and unrestricted instructors?
VT