That's because marine stuff is expensive enough to actually have profit margin built into the price, also it tends to be over engineered because of the environment it has to work in. If it was only just good enough when brand new in the marine environment then it'd probably stop working inside a year.I am more used to seeing marine fuse boxes which often tend to be more substantial and robust and probably more simple as well.
vehicles are one of the most aggressive environments, heat, salt, damp, acid, Vibration & pressure washed with truck cleanse
Boats are all of that and then some, the wiring on most 10 year old cars is still in good shape, I've seen plenty of completely knackered wiring on boats that's less than a year old.