Food poisoning has much slower onset than most people think, and, as I understand it, it’s very common to blame the wrong food.
I think it would be good to encourage everyone with food poisoning to notify a central authority to collect statistics, but blaming a specific restaurant from a single case is dicey at best.
It’s also worth noting that most people expect meat to be the riskiest type of food. In fact, lettuce is much more likely to cause food poisoning.
(Ground beef is indeed more dangerous than solid pieces, but most chain restaurants are pretty careful about their HACCP and are likely to cook it properly. Your average large burger chain won’t serve rare beef patties even upon request.)