To be clear, it absolutely DID happen. An old lady did in fact spill coffee in her own lap, she did sue McDonald's, and she was awarded nearly $3 million in court. All of that did in fact happen.
The problem is, the devil's completely in the details in this case. Like most people, I didn't know until years later that she received skin grafts for the 3rd degree burns the coffee gave her, or that McD's coffee was so searingly hot that over 700 people had complained of burns, or that the old lady and her family were essentially goaded into suing McD's by McDonald's themselves. Or that they only asked for help with the medical bills, and that the $3mm was reduced by the judge. All of these things are true, too, but as the article says, the media just picked up the Hot Coffee = Millionaire angle and ran with it. Like most people, I pictured a greedy old lady spilling some rather warm coffee and gleefully pocketing handfuls of cash, thanks to CNN and late-night comedians.
So, while the full truth is awful and shocking, it's also sort of silly to say "it never happened", because it did.