Here’s how Sack-Town does it:
You can see the three varieties in the bottom of the image. This is some pretty weak tea.
Fun Diego has a much better approach – real letter grades.
And Frisco, well, the Golden Gate Restaurant Association thinks all its members are above average, so it hasn’t deigned to allow SFGov to impose a letter grade requirement on food places in the 415. So why does the GGRA have such pull? IDK, that’s just the way things are.