I was dumbfounded to see NO ONE on any of the boats doing a dive plan or a buddy check.
Learn something about gas management, other than "be back on the boat with 500 psi".
Have a dive plan. It doesn't have to be complicated, but it should be more than "jump in the water and swim around until the computer tells me to come up".
This is the real problem. I'd bet that most on that boat don't have the knowledge to run through a dive or gas plan. That means they lack an understanding of dive science and its risks. Sadly, most of the major agencies encourage this type of behavior. Regardless of their written training materials, many resort certification factories have people jump in, swim around until their air gets low, and then get back on the boat. Do this 4-5 times and you get a new cert card mailed to you.
Just an anecdote: I dove with a "reputable" PADI diveshop in Roatan where the divemaster told us that it was OK to get back to the boat with 200 psi.