First aid kits are for convenience. It's convenient to put a band aid on a cut. It's convenient to tape a bandage to a skinned knee. It's convenient to have a safety pin or ointment. But you don't really need any of that stuff.
A trauma kit is for those OH S*** incidents that are life/limb threatening. CPR mask, tournaquet, compression bandages, occlusive dressings, needle n thread. For when unusual stuff happens. Gunshot, impalement, amputation. Very few first aid kits have this stuff especially not small kits for day trips etc.
For other traumatic injuries, no first aid kit is gonna do much for you. Many of these injuries are caused by gravity. Head injuries and other internal injuries from falls or crushes, compound fractures, etc.
Heart attack, stroke, clots, heat stroke, dehydration, hypothermia, venomous snake bite... none of those can really be treated with a first aid kit.
In the more serious scenarios, you're toast if you don't have evacuation/transportation, communication, or equipment available. If you're in a group, someone can run for help. If you're alone, take pictures.
The reality is, a basic first aid kit is just a convenience for cuts and scrapes.
On a day hunt for example, the most likely injury you'll have is a cut or scrape. Next is probably a twisted ankle or worse a broken foot/leg. Then maybe snake bite. Prepare for the most likely scenario.