Sorry, what?
How is this OK or even normalized - he should not have to check every single receipt every night. You hire people to do that, and if they cannot do it right, you hire someone else.
As OP mentioned, it wasn't a gradual thing, and when you have a lot of customers, it can easily slip through. Even your father would be the same here - if a few people who should have been charged a recurring bill did not, how would he remember that?
> Every good business owner does it.
Absolutely not. Every good business owner gets someone to take care of it, and then double checks their work at times.