So expectations of care are higher, but that might be better stated as "effectiveness of care", since the cost of effective care is generally higher than that of nonsense. "medicine" that is just a slurry of alcohol, cocaine, opium and some random herbs for flavor is much cheaper than a precisely measured dose containing X micgorgrams of of a highly refined, synthesized ingredient.
Another factor here is that the insurance only covered the worker themself, not dependents. A sailor with the good insurance has a kid get sick? That sucks, hope they can afford the doctor out of pocket. So in that sense the expectations of care are much higher.
Speaking of children - the infant/childhood mortalitry rate was appalling, somewhere between 1/4 and 1/2 of children died. A lot of people were disabled early in life by disease and injury. It took good health and quite a bit of luck to survive long enough to become a sailor - the population that was sailors would be relatively healthy to begin with, making the costs of medical intervention average lower. Related, since this only covered active sailors, old folks and all the ailments of aging weren't factored into the costs.
Similar to the previous point - first aid, emergency care, and transportation have improved dramatically. If you get injured in the middle of the ocean and can't survive a week to a month in a dirty ship with diseased crew, you don't contribute to the costs. In 1798 if your hand gets ripped off by some accident or another, they aren't remotely capable of getting you to help without pointing the ship in the direction of a city with a hospital and waiting for the wind to get you there in a few days or weeks - no medevac, no coast guard, not even calling for first aid advice. Even if people then had expectations to match modern ones about a reasonable attempts to provide care - the capability of the times was such that a huge number of people would die long before care could provided at a hospital. So, insurance costs were much lower because a huge number of payees would never survive to take advantage of the benefits they paid for. (Heck, scurvy was still a major problem in ocean voyages, and a large number of the crew of any ship could/would die on a voyage - all of whom paid for the insurance. Limes had yet to be discovered or something).
All of this of course is in light of modern views of pricing and salary - which itself is a pretty hard comparrison. In general most of a person's pay went to food up to 90% (or more) - leaving little room for anything else, and so prices and margins (and expectations thereof) for non-food were much different. For the most part in the US food is a much, much lower percentage of a person's expenses anymore, so it's hard to do a direct comparrison.