There is quite a bit of difference between someone caring about what is, to them, a significant inconvenience, which is I think what you are describing with those who send angry missives about services, and those who nitpick everything constantly, in many small complaints, like the overly needy customer in a services industry.

The angry message to a tech service provider can often be a last ditch attempt at resolution. An angry review of a restaurant is usually little more than a public “fuck you”: they aren't getting further business from that customer.