That is the point in a first world nation close to trauma centers or a military environment where you have assets and care who can respond.The point of BA is to not have an immediate kill impact on your vitals. While yes you can die from an abdominal wound, in most cases that won't kill you instantly. The point of BA is to be able to stay in the fight long enough to win the fight or get to safety where you can get medical attention if you need it.
There are ALOT of scenerios where getting hit outside of the plates will be fatal. Everyone needs to evaluate their needs and risks and make decisions based on that.
I used to outfit Federal LE officers who would routinely be 3-4 hours from the nearest responder BEST case scenario. That's assuming they actually have working coms and can call for help. A 9mm round to the side or bellow the plate could very well be fatal by the time they get to advanced care.