I think there are plenty of instructors out there, from whatever agency, who do the absolute minimum to satisfy the standards and cycle through as many students/courses as they can.
I've seen more than a few instructors who are, themselves, a danger to themselves and others. How are they supposed to ensure a satisfactory result for their students?
IMHO, the best way to ensure quality (and safety) is to ensure that instructors are properly paid. At this point, the emphasis changes from desperation to earn a subsistence income... to being selective and discriminating about who attends training and who graduates training.
The same is true of dive operations - who can be a big factor in placing undue pressure on instructors to achieve 'volume' turnover, regardless of student competency etc.
It's wrong that so many instructors and dive operations globally are forced to prioritize income over student quality... but that does remain one of the biggest pressures on an instructor...and one of the biggest barriers to improving course provision.