Thats more of a "no prices on the physical menu in the restaurant" thing.
No prices on an online menu is more likely to be because the restaurant has multiple stores and the different stores set their own pricing based on their costs. Much easier to just leave the pricing out altogether than require the user to pick their restaurant, and potentially complain about why item X costs more at their restaurant than it does at the one in the next state over. Not to mention a lot more time consuming to put all that onto the website and keep each price for each restaurant current.
No prices on an online menu is more likely to be because the restaurant has multiple stores and the different stores set their own pricing based on their costs. Much easier to just leave the pricing out altogether than require the user to pick their restaurant, and potentially complain about why item X costs more at their restaurant than it does at the one in the next state over. Not to mention a lot more time consuming to put all that onto the website and keep each price for each restaurant current.