Haha, I laughed about you can't smoke and poop part. Funny observation.
It seems to me that since bathrooms are not designated by smoking status and are much smaller, enclosed spaces the smoke would be more condensed and offensive to non-smokers.
The smoke in Vegas casinos and clubs has always bothered me even though I get that it's a part of the culture. I'm guessing casinos allow people to smoke while they gamble because the longer people sit in the chair the more money the casino makes. Smoke breaks are probably bad for business.
I also live in a city where you can't smoke anywhere, even in some places outside. It's always a shock when I'm in smoky places because it clings to everything, makes my hair and clothes stinky and makes me wheezy.