I'm not sure though that even a CPL holding non FI/CRI could conduct this flight legally as it would surely be construed as non-instructional 'aerial work' and need to be under some form of operator's certificate?
'Being paid' for flying isn't the whole situation. For example, the attempts by some to employ well-paid 'gardeners' to cut the grass outside the club house once per week but just happen to be PPL holders with FI ratings has been tried on in the past....
I agree with your explanation of the rationale behind the cost-sharing restrictions.
As I've said before, there are plenty of FIs and FI(R)s available to do any amount of 'trial lessons' and 'check rides' for general club work - so clubs should darn well use them and keep on the right side of the law.
(Private owner group internal policies are a different matter, I grant you. So long as no dodgy deals are agreed, of course!)