I am a DM for my local shop. The instructions from my boss are: I do not lead anyone a dive that is deeper than their certification limit. If they only have OW, that limit is 60'. AOW, the limit is 100'. Full Deep specialty, the limit is 130'.
Sorry, but your shop is wrong. Limit to any recreational diver is 40m/130ft. Limits you specified are recommendations, nothing more, nothing less. For example, my current rating limit is pPO2=1,4 bar, so 56 m/180 ft on air. Of course I am not going that deep, without further training or, more likely, never, but those are the limits.
Your boss could say, don't take them bellow certain depth, because I said so and I have every right to put whatever limit I think I should enforce, but don't put it on agencies.
Great points brought out here. Another reason to do the AOW and may I say the Nitrox class is to avoid the limitations placed by certain charters. I've seen charters not only limit a diver based on AOW certification, but the charter has denied a diver access to the boat without nitrox certification. Get the courses/ knowledge base the charters are looking for and avoid this confrontation.
Reason I took both cards. Second reason, to be covered in case of insurance claim. Turns out, DAN standards recognize certification and/or experience, so I could basically go down to 40 with OW and some mentoring.
I went the other direction. After teaching for 12 years I retired and became a mentor. I'm currently mentoring a young man who became certified just a few weeks ago. We've so far done a half-dozen dives together. I am not trying to be a substitute for a class ... quite the opposite, in fact, I'll happily refer him to an instructor if his progress indicates that a class would be a good idea at a given point in time. I just take him diving, talk to him about what I see him doing and how he can improve his skill set, and primarily try to set a good example ... most divers, especially new ones, can learn a great deal by simply watching what experienced divers are doing.
I enjoy diving with newbies ... they have a way of keeping me from taking anything about this activity for granted ...
... Bob (Grateful Diver)
That is how most of clubs here work. Right now, I'm on AN, or, to be more precise on Extended range Nitrox, two OW divers from my club, with basic Nitrox were out-flat refused this course, because of their current skill level. According to standards, they are OK, but as instructor put it: I wold certify you for dives I would not be comfortable to be buddied with you for.