….When I questioned whether this was true of ALL dive ops on the Great Lakes,
Depends on location. In my Chicago-Milwaukee zone, the real estate near piers is too pricey to support retail LDS and the easy access that would provide. The physical transport of heavy rental stuff (tanks) then becomes an issue.
Dive boats mooring slips- not at the street area, have to hump the gear down the wharf. These factors often force individuals to perform both of those functions. Sometimes the boat will have a hand cart For group use.
These divers are heavy metal. Not generally prone to single Alu80’s. Weight harnesses all trimmed out. Manifold doubles or 120’s. In this area, we’re catering to a DIY group for all those reasons, and more.
This OP was really about “marketing“. In that vein, the connection between LDS and Dive Charters was very established from the 1970’s. Some LDS owners went vertical integration and owned their own dive boats, no small thing as many found out. The Dive Boat captains also dabbled in some retail (largely in Milwaukee area) and provided gas at their ‘shop’.
[ consider this: in the Caribbean Model, a resort that contracts with an off-prem dive service provider, the boat comes to the resort laden with pre-ordered simple BCD set-ups. See the difference and similarity? ]
This 70’-80’s time period also gave us a shift from 7/8” wetsuits, to the exotica of the primitive and expensive early dry suits. Now, it’s the norm, rarely rented, usually advanced quickly to ownership, more personal crap to haul to the boat.
As the diver population that would tolerate the Lake Michigan “experience” waned, as the Caribbean changed from exotic, pricey, Clutch Cargo to Club Med, more cold water divers got ”too old to be cold”, so LDS switched to selling (or renting) WWPF rigs and doing Caribbean trips- easier for the LDS rather than local cold water diving. Easier money, easier sell.
LDS parking lots changed from Pick-Up Trucks to SUVs.
The divers learn the Dive Charter Boat’s boarding process and approved methodology for gear transfer pretty quickly. The DMs will likely
CONCIERGE the clumsy, unknowing or clinically stupid. Space and safety are a consideration. Then, the guests have to hump their non-stowable containers back to their vehicles.
This is where all the Milk Dairies store those plastic milk crates between deliveries.
In this Milwaukee-Chicago zone, there’s a lot of personal effort, not so much concierge, but arguably catered. These divers are really good divers, there is no margin for stupid.