> Google might be able to create a such directory based solely on traffic and AI identification of the type of business? Could AI identify long lines outside of restaurants?

Google already does plenty of stuff like this, and has for years (including historical and live busyness). Hell, I haven't used Yelp in years, because their app is generally less usable, isn't integrated with Maps (for directions etc), and cripples mobile web by not letting you see most of the content. Though it's possible that the data for G Maps is only comparably rich because of my location, and that Yelp has a data advantage in many more markets.