If a 7-11 store is open 24 hours a day, 7 days a week, 365 days a year, then why are there locks on the doors?
The doors are mass-produced with locks.
In case there is a situation where no employee can be there (everybody got sick all at once, the only employee scheduled to work has a personal emergency)
In case of a large-scale emergency requiring evacuation.
'Cause it only costs a few bucks to install one, and you never know.
Some possibilities
