Land of the free, unless your actions cause harm to others.
They've done studies on non-smokers who work at bars in NYC and Ireland after smoking was banned. After a short time, they end up healthier and have lower levels of a known carcinogen found in cigarette smoke. Some would say "let them find another job, then." But, if you look at the history of workplace safety in the US, it's almost ALWAYS legislation that leads to safety standards, minimum wage standards, environmental safety standards, etc etc.
It's less about the patrons eating there on a night where someone next to them lights up, it's about the people who don't have much choice in the matter working in an environment that is not good for their health.
My father grew up in the 60s and did lots of drugs (still smokes weed) and smoked cigarettes until I was in my early teens. He hid his smoking habits from be the best he could until I was maybe 19 or so, though I had found out beforehand that he was a smoker. He knew "do as I say, not as I do" isn't the best example, so he took it upon himself to sit cooped up in his bathroom with a window open on the toilet to smoke his cigarettes. It helped keep me away from smoking and drugs (I've never done anything, ever) and I'm glad he did it.