A restaurant is not public property.......it's a private enterprise.
O.K. Let's carry your example a bit further- What about funeral homes, churches, busses to transport T-ball teams? Would it be reasonable to light up some carcinogenic material in any of these settings? What has happened is that the pendulum has slowly swung to where we are now- the case being that tobacco smokers can (at will) light up their air polluting substance in close quarters with those who had rather not breathe it. So, what is a person who want's to breathe clean air to do- quickly depart the area?
O.K. What if my choice in combustible materials were oak or sycamore leaves or pine needles? Should I have the right to light up "my choice" of smoke producing substances in "smoking allowed" areas?