This coffee was being over-brewed at higher-than-normal temperatures because the McDonalds franchise was being greedy and attempting to extract more coffee out of the grounds.
This exact same franchise had gotten past customer complaints about the dangerously hot coffee burning people.
I and my father have spilled decent amounts of normal temperature coffee on our laps in the car, it barely caused any burns at all, let alone third degree.
The coffee was excessively hot and the franchise was negligent.