It is pretty reasonable for people to say that the OP should have hired a private DM. If the dive op had insisted and he refused, then it's all on him. Otherwise, the dive op told him that they can meet his needs, so he had no reason to believe that they couldn't or wouldn't- until they got to the site. Sound like they were geared up and ready when the DM told them they were at a different site than briefed. OP can you clarify?
It is, however, absolutely his responsibility that they did the dive anyway. Do not get in the water if you don't want to. That being said, having the skill set to thumb a dive anywhere anytime is a one that is learned with experience. It can be tough- although still your responsibility- to call a dive when you are a novice. In the climbing world, not backing off a climb and exceeding abilities is a leading cause of accidents. (read the yearly published book "Accidents in North American Mountaineering" and you'll see "exceeding abilities" as one of the causes on many climbing accidents. Learning the difference between being nervous because you are puckered at the prospect of the climb - but knowing it is within your capabilities- and being nervous because you are about to exceed your abilities is not an easy difference to learn. And often you cannot learn the difference if you don't earn some wisdom along the way by screwing up.
One reason this happens on the big routes is that some people travel really far to do a big route- El Cap or Alaska- have a short window in which to complete the climb and don't want to descend because they spent a lot of time and money prepping and getting there. Same with us destination divers. Still you thumb the dive or back off the climb if necessary.
On a different note, I have had people attempt to fleece money from me all over the world- including Canada and the US. It is not a phenomena exclusive to Mexico.
It is, however, absolutely his responsibility that they did the dive anyway. Do not get in the water if you don't want to. That being said, having the skill set to thumb a dive anywhere anytime is a one that is learned with experience. It can be tough- although still your responsibility- to call a dive when you are a novice. In the climbing world, not backing off a climb and exceeding abilities is a leading cause of accidents. (read the yearly published book "Accidents in North American Mountaineering" and you'll see "exceeding abilities" as one of the causes on many climbing accidents. Learning the difference between being nervous because you are puckered at the prospect of the climb - but knowing it is within your capabilities- and being nervous because you are about to exceed your abilities is not an easy difference to learn. And often you cannot learn the difference if you don't earn some wisdom along the way by screwing up.
One reason this happens on the big routes is that some people travel really far to do a big route- El Cap or Alaska- have a short window in which to complete the climb and don't want to descend because they spent a lot of time and money prepping and getting there. Same with us destination divers. Still you thumb the dive or back off the climb if necessary.
On a different note, I have had people attempt to fleece money from me all over the world- including Canada and the US. It is not a phenomena exclusive to Mexico.