I believe some of those early arcade games were more electrical engineering than software engineering, so perhaps it was easier to set it up that way?
To my understanding some of those early arcade games also had jumpers to control some of the behavior. It could be that a tech set the "free credit on reboot" jumper and forgot to reset it when they were done.
>>everfo+(OP)
Maybe they never reset it since it was too convenient to let employees just do it every morning, not sure, but yeah I think you might be right.