The Internet reminds of me of driving. Most people will scream at another driver for cutting them off on a merge -- assuming the driver was being aggressive and entitled (he thinks is time is so much more important than mine!). That same driver will find himself on a road, not paying enough attention, only to discover his lane is ending at the last second and expects another driver to let them in and understand it was just a mistake.
We scream because we don't see the other driver as a human being, just an angry caricature of a bad driver (and we're not actually confronting that driver directly). On the Internet, we'll rip a mom and pop or small restaurant business apart because of a server who had too many tables and one bad dining experience. That same person likely didn't talk to the manager or give them an opportunity to make the situation better because it's a lot less socially intimidating to hit Yelp and tear into them via a bad review.
[0] My favorite is "bed bug" reports at hotels. Practically every single hotel I've stayed at in the last few years has had at least one review claiming bed bugs (some with pictures for evidence). It's a problem pretty much everywhere and in those reviews I look for a hint about how the hotel handled the situation. If it was taken care of in a reasonable manner (regardless of what the reviewer feels was reasonable), I won't hold it against the hotel.