It's air hog standard and cattle diving operation standard.
Basically if you're running a turn and burn dive operation with the cruise ships as your main source of customers you run your dive operation differently. It's more along the lines of a factory assembly line rather than a custom built product.
You're going to get lots of vacation divers with vacation diver skills and air usage, newer divers, divers with low expectations. It's an easy demographic to please, if they see some fish, got to listen to some regae music on the boat and have a relatively safe and fun experience most cruise ship divers would consider it a successful excursion.
You run herd over your divers which can be similar to herding cats, lots of divers without the ability to gear themselves up, putting wet suits on inside out, masks fogging and leaking on dives, divers with horrible buoyancy skills and burning through their air supply quickly. You run your boats on a schedule, getting the divers assembled, out to the dive site, in and out of the water, on to the next dive site with the surface interval being the time it takes to get to the 2nd dive site and everybody herded back up and into the water for the 2nd dive, you get them in and out of the water and back to the dock. Shallow, quick dives help with short surface intervals between dives speeding up the entire process and reduce the chances for problems and accidents in the water as well as decompression injury.
It's just the nature of the beast.