Why do some restaurant burger photos show a knife stuck through the burger?

I've noticed that many restaurants put a steak knife in the burger on pictures.

1. This may be an example of a filter bubble. I just used Google to search for burger images, and of the hundreds of photos returned, not one had a knife stuck in it. So perhaps you clicked on a few burger photos that do include knives, or looked at a few restaurants that happen to server impaled burgers, and now Google thinks that that's your idea of a really appealing burger.

2. I can't dispute your search results, but I think using the word "many" is an exaggeration. Some restaurants do stab their burgers, but I think it's safe to say that restaurants that depict their burgers with a knife stuck in them are a small minority of burger places overall. It's only a particular segment of burger producers that would even consider it: sit down places (because you can't take that kind of thing out) that want to have something really impressive on the menu just in case Guy Fieri drops in with a camera crew.

3. If you're going to post photos of your burgers online, are you going to show a run-of-the-mill single-patty with Swiss cheese and mushrooms? Or are you going to show your signature Quadruple Deluxe Monsterburger Platter with the optional fried egg and bottomless fries? If you're advertising food, in the US at least, it's go big or go home.

4. The knife makes the burger look even taller and more impressive than it already is.

5. Nobody who isn't Paul Bunyan can pick up that Quadruple Deluxe Monsterburger, let alone open their burger-hole wide enough to take a bite, so a knife is both a necessary part of the package and a visual clue that you're meant to consume this dish in smaller pieces.

6. When people contribute photos to review sites like Yelp! or to social media like Facebook and Instagram, they want to impress their friends or readers. So they're more likely to post a photo of a burger with a big knife stuck in it than something more common and less interesting.