OK. Another question: to what degree is customer demand the cause of divers being taken to sites that are well beyond their skills/ experience?
I ask for this reason: when I was very new, I most definitely tended towards trusting the judgement of the DM/ instructor/ dive op a bit too much. On the other hand, I really didn't feel any need to do the 'bucket list' sites. I would have been quite happy with an op taking me to an 'easy' site if they thought that was best. I was (and I still am to a large extent) just happy to be in the water.
Am I the exception? Or are there dive ops (some, at least) who take customers to inappropriate sites because of /perceived/ demand for that, rather than actual demand? Having never worked in the dive industry, I have no idea -- I can only answer for my own personal preferences.
I'm not sure what you mean in making a distinction between perceived demand and actual demand.
In any event, consider dive sites like Belize's Blue Hole. The dive ops have created what amounts to an entire sub-industry of taking people on a dive that is "appropriate" for pretty much nobody. There are threads about Belize's Blue Hole where this has been discussed ad nauseam. Anyway, is the demand for Blue Hole dives perceived or actual? I believe I am in your camp, in that I generally don't mind a DM who is apparently competent and knowledgeable about the local sites sizing up my skill and taking me to sites the DM thinks are suitable for me. That said, I have dived Belize's Blue Hole.