I agree that for personal first aid kits, as others have indicated, it's always a good practice to actually know how to use the things you are carrying. Training is at least as important, if not more important, than the collection of "stuff" you have in the kit. Things are also tailored to the number of folks covered by the kit, duration of the trip, and how long before advanced help could reach you if needed. The basic day hike FAK I carry looks very spartan compared to the expedition kit we take when we're doing a long trek in the mountains.

In fact, your example of the AMK 3000 Marine kit is a good one for a situation where the normal EMS system isn't going to get to you for 24 hours or more. Imagine you have a bad accident on your fishing boat, for example. You're way offshore, and the weather has deteriorated to where the choppers aren't flying. You might be on one end of a marine radio conversation with someone at a Coast Guard station who has proper training, who says: "do you have ____ in your med kit?" If the answer is yes, you might find that you can be talked thru a procedure that might otherwise be impossible, or require some serious improvisation. I know we carry a pretty extensive set of supplies on my boat, even though quite frankly, most of the time we're just grabbing bandages and antiseptic! It's one of those "just in case" scenarios where I think the penalty of not being prepared is too high not to be well equipped. The other thing is, if you're taking people where you might be 24+ hours from the EMS system, land or sea, you better have some training, and have someone on your crew trained (in case you need the medical help).

Many of those Marine kits are also designed to meet certain USCG requirements for offshore vessels and liferafts. They must have certain items (including a decent handbook) to meet Coast Guard requirements.