Restaurant ratings are also a poor signal precisely because they're all relative to the restaurant type. You can't honestly say a 4.9 star McDonald's is better

Restaurant ratings are also a poor signal precisely because they're all relative to the restaurant type. You can't honestly say a 4.9 star McDonald's is better than a Michelin star restaurant with a rating of 4.8, but it could (and probably does) happen. In my city, ratings for Chinese restaurants almost inversely correlate with quality. The real quality Chinese restaurants have amazing food but absolutely shite service, and it's that terrible (yet oddly authentic) service that brings down their score. Meanwhile the Manchu Wok (sort of like a PF Chang's maybe?) next door gets a higher rating.