Blood type is included on military ID's probably for 2 reasons: cross donors (where you transfuse without typing it), and to get blood quickly to the patient. Why? Well, yeah, O Neg works on everyone, but it's also kind of rare. Best to save it for folks that are truly O Neg, or traumas where there isn't time to cross check.

In the civvy world, usually O Neg (and increasingly, O Pos) is given while the typing is pending - in emergencies. If a transfusion is needed non urgently, then it can wait for a typing.

I don't know what you mean about "no doctor will order blood typing based on history." If it's not useful and not going to change treatment, docs don't order it - for no other reason that they probably won't get paid for an unnecessary test. Same goes for docs in the military.