And you don't. You have no idea if these are local owners or not, where they came from, where they are going to, what their SOC charge was when they arrived/left, how long they stayed plugged in, etc. IMHO, your detective skills are a bit lacking.They DO have the data!
You only know some people are walking away (which, frankly, is intended, else every SC would be built 10mi from any services and the car would stop charging if the driver left the vehicle), and some people are returning after shopping.
Dare I say, this might warrant a "lighten up, Francis!" comment.