For an airplane to be certified they have to prove it can be cleared of staff and passengers in a certain amount of time(think it's 2 mins but don't remember exactly). I saw a video of them testing evacuation times on the largest passenger plane including lights out, smoke in the cabin and fake passengers.
I'm surprised ships don't have a similar requirement. A full size evacuation drill to prove seaworthiness of their system(say 45mins to clear the ship - Concordia started listing after 40mins for a time reference). Yes 8500 people is a lot to use in a test but some movies have had many more than that as extras so it would be certainly be a feasible option. Perhaps it's one of many reasons ships are not registered in the US.