‘Ratings relative’ means, for example, that an 18/20 pizza isn’t the same as say an 18/20 restaurant overall. Rather it is 18/20 compared to other pizzas.
In any category, a 15 means “really good”. A 14 is a place I would happily revisit.
My highly subjective ratings scale described:
Restaurants that hold themselves out to be good:
Pizza (ratings relative)
Ramen (ratings relative)
Pastries and bread
Restaurants and cafes to try
Bars to try