> Ratings measure how good a restaurant is compared to other restaurants in the same class because that is where their patrons' reference frame comes from.

In the US, ratings measure, in significant part, race/ethnicity/subculture from which the restaurants clientele is drawn, because White Americans give higher ratings for similar descriptive satisfaction levels than other demographics (tending toward not unacceptable = 5/5.). Asians give the lowest scores for similar descriptive satisfaction levels.