>>then the life-saving implications are tremendous
Are people in medical settings dying because of a lack of blood? It seems that unless you're in some exotic blood group you will likely find a compatible donor, and it is not clear as to severity of an imperfect match to rarer groups like the mentioned "Bombay" group.
Your parent is theorizing that people in edge medical settings are. For example, an EMT might not be able to give you a transfusion while you lay bleeding in the dirt, because they may not have twenty units of blood to spare in the bus.
Are people in medical settings dying because of a lack of blood? It seems that unless you're in some exotic blood group you will likely find a compatible donor, and it is not clear as to severity of an imperfect match to rarer groups like the mentioned "Bombay" group.