Why does a hamburger symbolize food?

I don’t know what the English text of this blurry “no food or drink” sign says, but I don’t care; I’ve covered the text aspect of these signs already. I took the photo because I wanted to talk about the food and drink symbols.

The bigger sign features a double burger; usually the burgers on these signs only have one layer between two buns.

The smaller sign features a stemmed glass with a bent straw, suggesting an alcoholic cocktail; usually the drinks on these signs are trapezoids with straight straws that suggest sugary, carbonated soft drinks.

Both of the stickers, thus, differ in interesting ways from the canonical or prototypical “no food or drink” sign.

Still, I wonder how the prototypical “no food or drink” sign came about! I’ve seen similar signs all over the world, in places where a hamburger (or for that matter, the fast food restaurant in general) is presumably not a domestic cultural touchstone, but a relatively recent foreign import.

These stickers are not what you think of when someone says “globalization”, are they? Yet their spread must be attributable to the increase in international trade and communication in the decades since the hamburger was invented.

When and how (and where) was the hamburger invented? I don’t know. Wikipedia has some guesses. If you’re really curious, I hereby inform you that are at least two entire books on the subject (neither of which, in all likelihood, I will ever read):

I’d say the second one is more likely to explain why, all over the world, those black/red/white signs depict “food” as a hamburger.