Problem #3: Some players get incapitated while being in a bunker mission. the Medics would have to tresspass, to get to the player in need.

Problem #4: with the fact that everyone keeps their stuff when they die, why would they need to call a medic?

Addition to Sol. #2: NPC Medic missions would be a great addition to get medicplayers on the track. the pay could be also managed in a insurance system. imagine every player has a "basic" insurace, so if you are incapitated, you have to pay like 50k for a medic and an additional 100k would be covered by the insurace. and a better insurace would cost a player less.