Rare Sign In Town

Hey... last weekend I went to my friend's shop for chit chat then tea time we walk to a restaurant just a few block away. We sit down outside the restaurant and order their Roti Telur (my firend told me the roti is nice) At first I want to share their roti to you all but when I saw their sign stick outside on their window I found more interesting to share more than their roti lah!!
This is a sign which very rare can see in town here.
Which telling the customers do not allow to bring outside foods and  drinks especially alcohol drink!!
Rare right.... I really never see got sign like that, We all know here don't have selling or serve alcohol many many years ago and non-muslim only can drink at own house! Some how this is not a chinese restaurant... if is a non halal restaurant I can understand lah but here why??