That's true, but the other side of the coin should also be considered. To my, admittedly uncertain, knowledge, it is illegal in most states for any business to declare themselves a smoking establishment. You cannot post a sign on your door that says "Smokers Only". And the same rationale applies: anyone wanting to work in that business, or enter the business, knows beforehand that smoking will be occurring, and shouldn't have any complaints because of it.
And for the record, I am a reformed smoker, been smoke free for over 17 years now and I'm glad of it. But I still don't like the idea of discriminating against smokers. I would venture to guess that more people die of second-hand alcohol related causes (victims of drunk drivers, for example) than do of second-hand smoke.