Yes, complicated indeed. For one thing, an injury/condition/disability that is related to a person's military service will generally qualify for treatment by the VA regardless of the individual's financial status (or whether they retired from military service). Lots of folks have hearing issues (though it has gotten better since all the services are now quite strict on use of hearing protection). I know very few servicemembers with extended infantry or airborne time who don't also have knee, hip, or back problems. Etc.
+! on the above my oldest son hurt his back jumping while in the 82nd AB bad enough no more jumping after that. He got transfered to a Striker Brigade at FT. Wainwright Alaaska went to Iraq twice. He received 2 Purple Hearts, medically retired as a Sgt first class E7 from the army with 80% disabilty after 14 years. I would stand up for anybody to receive VA benefits after that ordeal.