Completely unbelievable!  One would think after spending that much at McDonald's you could get some extra syrup.  If you were to compare it to going to an upscale restaurant it would be like paying a couple hundred dollars for your meal and then to ask for a refill on your coffee, only to be told,  "It will cost you another $1.50 for the refill."
I can't blame the order taker, because after all.  All they are is in order taker.  They're not taught to think on their feet when they're only making minimum wage.  It's clearly a management issue that's not being addressed.