Why No Outside F&B Allowed?

I was having TT with a friend at one of the Indian restaurant and I saw this sign the ? sign pop out from my head.(TT mean Tea Tarik)
I understand that No Smoking in the restaurant are because from the MoH. But have you ever think that why cannot "Out Side Food And Drink Not Allowed Inside"?
Most of you sure think that "If I open a restaurant you come in no eat my food but tapao from other and eat here... What's the point I open restaurant?  Better open a Park right!!!!"
To me..... I don't think in this way lah. It has more that than meaning there... First of all I think is because of the food you bring and makan inside there are Halal or not!!! What if you tapao pork and eat in that restaurant and using their spoon and fork? Ah... habis lah like that!!! All the spoons and forks in the restaurant have to buang sudah tu!! You say correct or not?
Secondly what if you eat the foods form tapao outdside kana food poisoning and later to blame you are makan at their restaurant!!! 
So this are the 2 reason I can think why their are not allow customer bringing F&B from outside!