So the armed robbers can lock the doors after they take hostages.

Society, kids. Society...

Actually, you never indicated upon which side of the door the lock was located. Such jewels are warranted when attempting a proper rejoiner to such a query. 

(Whew...my thesaurus just contracted a bad case of WTF on that one)

Two reasons. First, employees are trained to lock the doors AFTER a robbery. (True)

Second, employees are trained to lock the doors when they see the owner's entire family pulling up, unannounced, after their long journey from Bombay.  (This is also true)

One word: hostages.

To keep employees IN ?

With this one, you have to read the fine print. It says 24 hour convenience, but it does not say how many days of the week! Maybe they close for half of the week.

During a cash count, when changing shifts at night, they will lock the doors so no one will walk in and steal the money in both cash drawers.

You know, LL Bean in Freeport, Maine is open 24/7, and they DO NOT have locks on the doors...go and check it out sometime!

Hmmmmmm.....

Just in case Aakman calls in sick and Habib needs to step outside for a cigarette.

This list is funny. But I did work at a s#@$hole convenience store while in college. (I needed the cigs and beer and quality study-time.) The locks on the doors come in handy if there if the power goes out for several city blocks. You have to lock the doors to keep the dirtbags away from stealing everything that is not nailed to the floor. (PS- when did this website get so weak? No one can drop a colorful metaphor anymore - I mean CURSEWORD!)

To keep you out whenever its convenient.

So some idiot can lock himself out.

To keep out the hillbillies who keep claiming that they've been abducted by aliens.

REVISED ! First I want to say about any of the items on this list, I understand most are sarcastic, and I appreciate it as Irishgit is a very cool guy and has a wonderful sense of humor. But as for this review, I am going to answer seriously for those who really don't know why those locks are on there. :) ORIGINAL: There are several different reasons for this, first being the lock is made available in case of robbery, as the cashier is required to lock the doors until police arrive and take care of the crime scene. They are also used in case of hurricanes, tornadoes, etc. But Rebel is also right when stating that lots of times cashiers will lock up while going to the restroom. Also in Florida, it is the law for a cashier to lock the doors up if the 2nd required by law cashier doesn't show up after midnight. It is the law in Florida that all 24 hour convenience stores must have 2 employees between 12 midnight and 5 am. There are other reasons as well....

Even people who work 24 hours a day need privacy.

So the clerk can answer the call of nature when he needs to without being robbed.