I disagree here. It’s not the quality of the burger’s meat, it’s the carefullness, or carelessness, of how the food is handled.
You can get ill from top grade beef just as easily as low grade meat.
There is no chain restaurant I feel comfortable ordering anyless than well done. I’m not usually such a safety nut, I mean, I eat raw oysters and clams all the time with little abandonment, but I don’t trust any chain restaurant from handling it’s ground meat correctly 100% of the time. And because I would much prefer a medium rare burger, I generally don’t order a burger.
I know plenty of people who have never gotten sick from eating rare burgers. But, and this is from 1st hand experience, if you ever get sick from a burger, you aren’t likely going to try a medium rare burger again when dining out. It’s not a pleasant experience.