Why does Benihana not do Yum Yum sauce?

A staple at Hibachi restaurants is the sauce they ladle in to the containers set before you to dip your food in or if you so please you can pour it over your food. Every other and I mean every other Hibachi place I have been to offers Yum Yum Sauce as a standard sauce, but not Benihana. They go up when other places go down providing a truly unique experience, but why not this sauce? It complements the meat well, is a welcome addition to a pile of fried rice, and can elevate the vegetables in a way few other sauces could.

Not sure I am going to find this answer, I refuse to look online. It will ponder the mind but will not sway me away from the Benihana experience.