When princess riverdawg graduated from Catholic high school a few years ago, there was a valedictorian and a salutatorian and then an unranked list of students with “honors” who graduated with a 3.0 average or better. In large high schools with a substantial upper-middle-class student population, there might be 10 or more graduating students with a 4.0+ average in a college-prep/AP curriculum.
In my son's graduating class there were 7 of 35 with 4.0 GPA. The valedictorian was selected based on weighted GPA, with AP and concurrent college classes on a 5.0 scale.
I will say that grades were not handed out like candy and it was an unusual/exceptional class. At least 4 of the 7 scored 33+ on the ACT (perfect = 36), and they were all fighting to squeeze as many AP and college classes as possible into their schedules. There were three up for academic all-state (top 100 in the state), with one selected (not the valedictorian.)
Sometimes when you're dealing with small sample sizes, you get some big fluctuations.