So, when you say survey "most" students post class - what does that mean and what are other people's experiences of it? Perhaps this will help us dispel the "myth" or make it the truth.
In PADI's case, at least in the Americas (probably similar in other regions, I cannot speak to those areas, however), the goal is to send a QA survey to every new OW certified diver, as I understand it. The surveys are sent by email, hence PADI's current requirement that an email address be included with every certification submission. That is a practical, albeit obviously imperfect, approach. 1) Some students (say they) have no email address. In that case shops will often enter a shop email address and attempt to give the survey to the student directly; 2) Sometimes the student's email provider / platform applies spam filters that send the emailed survey immediately to electronic purgatory, and /or it ends up in a folder that the student never checks. My GMAIL set-up has a 'Primary', a 'Social' and a 'Promotions' folder. PADI emails go to my 'Primary' folder, but they could easily go tp 'Promotions' if I hadn't taken action years ago; 3) Some students seldom check their email - hard to believe for someone who lives on (business) email, but that is the case; 4) Some students have multiple email accounts and intentionally don't regularly check one or more of them (which may be the address that they gave to PADI); and 5) Some students receive the QA Survey email, and ignore it. I seem to recall hearing a PADI 'official' say that their capture rate is between 20 and 25% of surveys issued, which they consider to be good compared to general response rates, but which is obviously far less than 100%.
I did my OW and AOW years ago and honestly do not recall if I received a survey, by email or snail mail. I seem to recall completing some kind of written assessment of my AOW class. When I completed my Tec Deep certification in 2008 (2 students in the course), I did receive a survey (I do not know if the other student did or not). It was very thorough (I thought), asked very specific questions (which I now know related directly to specific standards, and I spent a considerable amount of time responding.
In recent years, I have had various students tell me they received a survey, after a) an OW course, b) an AOW course, and c) a specialty course. I always encourage my students to respond to surveys if they receive one. I also make a special point of emphasizing situations where my approach to meeting standards might not be immediately apparent - for example, I show students that I have a folding snorkel in the pocket of my wetsuit, when I do not have one attached to my mask. I point out that I have two signaling devices (a whistle and a mirror), also in a pocket of my wetsuit. I regularly refer to standards in teaching, so that students understand why I do certain things the way I do. And, I usually say, when I point out these things, that I want the students to know what I am doing, in case they receive a PADI QA survey.
A comment on the titular theme of this thread: The world is not a perfect place. Scuba training agencies (PADI included) are not perfect entities. I am not a perfect instructor. Agency standards create a framework (a construct) within which agency instructors can deliver a
consistent product from the perspective of content (if they adhere to standards), that
meets the goals of the particular course, and
promotes the safety of students (and instructors). Individual instructors can make a significant contribution to the overall 'value', indeed the 'quality', of the learning experience, based on their personality, delivery, educational skills, technical expertise, adherence to the standards of their agency, etc. So, a categorical statement, 'Its the instructor, not the agency', is probably not entirely accurate, any more than 'Its the agency, not the instructor' fully describes the outcome of scuba training. It is worth noting that, in the majority of reported cases that I am aware of where divers have been injured or died during training, the instructor violated / failed to adhere to standards in some way. Yes, there have been medical events during training that led to diver injury or death. But, those appear to be the exceptions. So, I think that agency standards are important. And, I also think that standards across the majority of scuba training agencies with which I am familiar are more similar (not identical, but similar) than dissimilar, notwithstanding some (well-intended) chest-thumping at times on behalf of one or another agency.
I spent 26 years as a tenured member of the facility of a major state university, in a health professional school with a national reputation for research excellence. I had a colleague, in another division, who was a friend, and someone I admired greatly as a person and as a scientist. He was world-famous for his work, had exceptional extramural funding, supervised multiple post-doctoral students, etc. And, he was an
absolutely terrible classroom teacher. He had no discernible teaching skills in that environment, was a poor lecturer in terms of organization and delivery, and not just because English was not his primary language, although that contributed to his 'performance'. I actually think it is safe to say (unfortunately) that he met 'standards' for university teaching - his syllabus ostensibly included the material intended to be delivered in the courses he taught, he nominally covered the material in the classroom, and he assessed students with written examinations. But, it was readily apparent, to other faculty and very painfully to students, that he should not be in the classroom. I have seen some scuba instructors fully adhere to their agency's standards, and deliver a very poor product. I have seen other instructors adhere to the very same standards and deliver an inspirational product, that leaves students excited and wanting more. I have also seen some very 'personable' instructors fail to adhere to (aka violate) their agency's standards, because they were lazy in some cases, or simply thought they 'knew better' in others, and certify students who were lacking in some expected skills. Standards make a difference. So do instructors. And, those are not myths.