Why so chintzy on the Coke?

Every casino that I know of provides free drinks for their gamblers, including poker players. That's nice. But I can't figure out why they're so stingy with the Coke.

Coke is my only vice, really. I don't drink, I don't smoke, I don't do drugs. But I loves my Coca-Cola. (Pepsi will be tolerated in an emergency, but with my nose turned up.)

The problem while playing poker is that essentially every casino offers me an itty-bitty glass that is filled to the brim with ice, followed by a little squirt of Coke thrown in as an afterthought. One swallow and it's gone.

I don't get this. I could request a Red Bull, which probably costs the casino a buck a can. I could request whiskey or vodka or a decent beer, all of which the casino would presumably get for me. By comparison, Coke is dirt cheap. At any 7-11 store, you can buy a Ginormous Gulp (or whatever they call it) for, like, 79 cents, and it's about the size of a 55-gallon oil drum. I assume that they're making a profit on the stuff, even after paying for the several pounds of plastic it takes to make a cup that big. Nobody can actually drink that much, at least not without having a urinary catheter surgically implanted. And if you did, the caffeine jolt would be like getting a cardiac jump start from a Nevada Power high-voltage transformer.

So the manufacturer obviously sells the syrup for the dispensers pretty darn cheap. It's probably even cheaper for them to give me a glass of Coke than a bottled water, for Pete's sake. Why, then, does the casino treat the stuff as if it's liquid gold?

Can't a guy get a decent glass of Coke in this city?