Why did it take so long? Well, it started with the customer who wanted to purchase a propane tank. They're kept outside the store and have to be unlocked with a key. For some reason, no one was available to unlock the tanks.
Now, I imagine the usual way of dealing with this without clogging up the line would be to ring up the rest of the customer's order and send them to the customer service desk, but I've never worked a cash register so maybe I'm wrong on that and maybe it is Wal-Mart's policy for the cashier to find a phone on another register and spend twenty minutes trying to locate a manager who can find the key.
But you know it gets worse, of course, when the cashier is talking to a manager and you hear "I'm sorry you don't want to look for it, but I have a customer waiting so could you please take five minutes?" coming from the cashier's end.
So finally the key's located and the customer gets her propane. Then the next customer in line has problems with her food stamp card. This is not a suck; it just happens sometimes, and the customer was polite and tried not to hold up the line.
But please, Wal-Mart cashier, when this poor woman leaves to try and find an alternate payment in her car, which I assume is a very embarrassing situation for her, and you can't figure out how to cancel the order, this is not an excuse to turn to me and complain about how awful this woman is an how she's holding up the line and making everybody wait. Yes, it's the poor woman on food stamps' fault, not the fact that you spent twenty minutes looking for a key to the propane tanks and the managers couldn't be arsed to help.