Why would the temperature differ for ground vs whole meat? Surely the same temperature would have the same ability to kill bacteria no matter the way the meat was processed.
Because there's lot of bad stuff that's external to the muscle that can wind up on the surface as a result of the butchering process. When you grind the meat you potentially mix that throughout so you gotta cook it throughout whereas a steak can be eaten raw-ish in the center.
This is how ground beef e-coli outbreaks work. People don't cook their burgers through and get sick.
