Maybe the world is more then the USA, so if in country X a doctor finds a person with something and he wants to warn all the people this person had contact with

Maybe the world is more then the USA, so if in country X a doctor finds a person with something and he wants to warn all the people this person had contact with, this doctor would have to ask nicely Google and Apple to grep trough logs and find who meet who and where? Would Google and Apple respond to a doctor in a small country? You can have a national app that is under the control of the health department and doctors ,t hat only does things like "send a notification to all users that were in contact with person with this ID to come to hospital and get a test". I understand that this could be potentially abused for evil or that evil people already do this using WiFi or cell towers, I am thinking that we should also think at the good that could come of this.