Just some basic stuff, I think we all know this?
In the US, you can carry passengers for hire, but if even one of them pays for that carriage, the Operator / Captain must hold a commensurate license, "operator of uninspected vessels" as a minimum. The "smallest" of these is for no more than six passenges, hence "6-pack".
If you carry more than six paying passengers, then the boat itself has to be inspected, which means not just equipment, but the build itself has to meet the Small Passenger Vessel Subchapter T standards, i.e. collision bulkhead, stability letter, watertight doors, much more. Way way back in my trainee-inspector days, the old-salt instructor shorthand was, "you can drown six-- you can't drown seven".
And the captain's license must be for "Inspected Vessels" up to a certain gross tonnage, which vessels have a Certificate of Inspection ("COI"). So, the "6-pack" license won't suffice, nor would any license that is for uninspected passenger vessels only.
And that COI is for vessels built and registered in the US, typically via a Certificate of Documentation. The Jones Act provides that US-flag only can carry cargo or passengers "coastwise", meaning from one US port to another (and probably to and from the same port, which is what the dive boats and oilfield crewboats and supply boats typically do.
And yes, I have to admit that historically, any reforms or improvement in safety for US vessels (and other countries' too) have followed a major casualty, and don't precede it. So yes, as one earlier commenter here has said, in general the marine safety regulations are indeed "written in blood". Why don't see ahead to that accident waiting to happen? I can't answer that. Maybe a sociologist (or in some cases an accountant) can?
Let's look at the record, at least what I remember or learned, about improvements that resulted from a particular tragedy on the water:
Back in the 1860s, the (overloaded) passenger riverboat SULTANA, awful fire and great loss of life after a boiler explosion: -- Licensing of Engineers, and improvements in boiler safety valves.
1903, the passenger boat GENERAL SLOCUM in New York, fire causing over 1000 deaths. -- improvements in fire equipment and hoses, and inspection standards.
1912, TITANIC, improvement in watertight compartment standards, International Ice Patrol established, radiotelegraph requirements, and of course, enough lifeboats for all passengers and crew.
1934, Passenger liner MORRO CASTLE, caught fire (probably arson) and burned through during a storm, grounded on a New Jersey beach, 137 deaths. ---no more beautiful (but flammable) wood-construction interiors; fire-resistant materials required thereafter, and alarms rather than relying solely on fire watch rounds-makers, at least for US liners.
1956, ANDREA DORIA / STOCKHOLM collision in fog, DORIA sank, 46 deaths: -- advancements in radar plotting and radar use, establishment of shipping lanes in areas of traffic convergence.
There are a whole lot more. Yes, "if only" we had forseen and regulated-in-advance preventive measures, instead of afterward. We may add "Conception" to this list now, albeit for a very small number of vessels. New regs coming (I believe there's already a pro-forma bill in the House?), but short-term, night watchstanders actually being there, and being watchstanders--and walkers.