They do publicise what is on offer, they have a full menu and also images of the restaurant and a place to ask for pick up and drop off. They are also very successful.
Other places, such as Vojo's (now gone) did just have Facebook Pages and did not have menu prices, but the F.B.Page was very popular and helped to get them business. In fact, even without prices they were still No.1 in Calis Beach. The moral is, publicity always works.