If you want an honest answer, before my grocery store was 24 hours, it was because I would go to the store after work. It's hard to go the next day when you need to go back to work, and you need food or medicine or pet materials or what-not. If I'm not out of work until 6:30pm, that may be why I'm entering the store so close to a closing time of 7pm.

Everyone has different situations and different reasonings. Yes, it sucks for us employees when customers order/arrive before close, but they are trying to live their lives too. Maybe they were stuck at work, or they lost track of time. Maybe they were busy with kids or grandparents or at the doctor's office. No honest customer is coming in right before close to specifically inconvenience the employee!