You would've loved the little old lady I used to work with at Target years ago. She'd give you a big old smile, dry off a shopping cart for you, find the offending item that mistakenly set off the alarm for you, and more. Of course, the second you were out of earshot, she'd say the worst things I ever heard someone say about a complete stranger; but hey, you got the smile you wanted.
LOL, I would probably be wondering why my ear was ringing after I let that Target.
With the posts I've been seeing here, I would think none of you have worked in any service industry for the last 15 years. While the cashier in the OP was definitely in the wrong here, it has been my experience more often than not that the customer is usually imagining being wronged or expecting way more than they should.
I don't imagine much. Considering I probably should not be eating at fast foods as often as I do anyways, I have a system I have been forced to create and constantly update every time I order something new. When ever I go thru the drive-thru or the counter I always have to check to make sure I have the correct amount of items I asked for. I sometimes make sure I even got them they way I wanted. I will also check to make sure I get the drinks I asked for and if I got milk in my coffee. Ketsup, BBQ sauce, napkins and straws should never be left out of my bag because I will notice quickly. I pretty much will not walk away from the counter or drive-thru window till I'm sure I got what I asked for. Too many times I went home not checking I 50% of the time coming short on items. I can tell they sometimes get upset when I stand there checking the bag but I couldn't care less Even worse, I had the bad luck the store I bought the food from was not the closest one to me.
I only expect what is advertised. Fast, friendly service, decent food, the correct food and price and most of all, hot food, even if its from a microwave.