[GuiA]

This could be a cultural design thing. A lot of these apps (Airbnb, Lyft, etc) are from the US, where getting full marks in school is a frequent occurence if you study reasonably well.

In France for instance, it's very rare for a student to go above 15/20 or so at the college level (I graduated in the top 10% of my class with a 12/20 average; the top ranked student, whom I was friends with, had a 14/20 average).

But when I graded homework as a graduate student for an american university, the professor told me I was too harsh, and after adjusting my criteria to match what she wanted, I found myself giving many 100/100.

[notahacker]

The US is also where you insult service staff and deprive them of income by giving them a gratuity which would be considered generous thanks in most tipping cultures. But at least that's baked into one's understanding of the price.

When it comes to ratings used by others to evaluate, no system is more customer and vendor-hostile than one where everything that meets a minimum threshold for adequacy should be rated as perfect.