I’m reminded of a chestnut I was once told; satisfied people generally do not post comments, because people don’t go out of their way to say that things are okay, and your everyday person doesn’t even really post good reviews unprompted, because good service is usually the expectation.
People only really get active about bad divergence from expectations.
I suppose what I'm trying to say is that in the case of positive opinions, it's not super common to leave them unprompted (see: all the popups in apps for "Like our app? Rate us on the app store!") whereas people angry at bad service have no compunctions about finding somewhere to vent, in public if they have to, and are super driven by their agitation.
People only really get active about bad divergence from expectations.