The flying school & ALL it's staff should be bending over backwards to keep the 'customer' happy, so that they can keep the ongoing business & also get any referrals that the customer might be able & willing to give.
Clearly there is a mix of tongue-in-cheek humour and offended sensibilities throughout this thread.
Unfortunately, some activities have the potential for serious and adverse consequences and the buck-stops-here scenario applies. Piloting, I suggest, is one such and much of today's aviation problems show a correlation with spoon feeding PC training attitudes. Other fields which come to mind include surgery and matters submariner and other critical military activities.
While the whack-over-the-back-of-the-head approach has had its day - I might add I have never used that sort of technique myself - sometimes the poorer achiever needs some direction.
I am probably a lot more generous and patient with my instructing time and enthusiasm than many but, at the end of the day, some folks just do not suit some occupations for whatever reason and need to be shown the door.
In my case, I have been lucky, I guess, in that I have had to scrub very few. Two of the more notable (including an experienced F28 captain upgrading to the 732 - he ought never to have been in command of a dinky trike), I referred to Exaviator for their final scrub rides.