5 - The Granfalloon

I was wondering today, as I enjoyed the Black Bean Burger at The Granfalloon, what might be the thought process behind adding a veggie burger to a menu. Of course, it makes perfect sense at a burger restaurant where they have a variety of burgers. Or, maybe at a a vegetarian restaurant, duh! But, The Granfalloon is not really the kind of place that caters to vegetarians, and I wonder how often their veggie burger even gets ordered. Do any meat eaters order it?
We scrutinized that menu; just about every other item had blackened chicken breast on it. And, aside from a couple of appetizers, the only veggie options were the Black Bean Burger and a veggie pizza. It didn't seem at all like the kind of place where a lack of veggie options would be noticed. And yet, they have a veggie burger. And it's not just a plain burger either, it's spruced up a bit with a nice touch of caramelized onions and roasted red peppers.
So, how does it happen? Does a bar owner say to the chef, "we should add a veggie burger." Do enough people ask for it that they finally decide to offer one? Or, is it simply becoming the norm? Who knows.
No, really, who knows? Anyone?