Nah, more likely he accidentally discovered it one day when he pulled on a 20 or a 50 or something that he didn't mean to put in there and pulled it back out before it went all the way in, then noticed that it refunded his money even though he still got the bill out. Then he devised a way to repeat that at will. i think an employee would have known there were cameras looking right at his face. He was making no attempt to hide.Start looking at the employees of the company that made the machine.. probably a backdoor.
... the man used a $20 bill that was coated in plastic and attached to something similar to fishing line. The suspect entered the coated $20 bill 35 times and voided each car wash purchase to trigger a refund from the machine. Each time, he was able to pull the coated bill back out of the machine. By the time the thief was done, the machine was missing $700 in $5 bills.
I "know a guy" who did a bunch of car was systems once using PLCs and did put in a back-door way of getting a free car wash for himself (sensor code pattern that triggered it). In his back door, he also included a defeat of the sensor that counted cars, so they never saw his nighttime freebies.
Interestingly, the guy seemed to be unaware that the machine had a camera filming him...
Somehow I think this all started with a drunken conversation in a pub...
...believes the man used a $20 bill that was coated in plastic and attached to something similar to fishing line. The suspect entered the coated $20 bill 35 times and voided each car wash purchase to trigger a refund from the machine.
I mean, is that worth the risk for a car wash that costs $15 - $5 dollars?