I feel like that’s quite possibly the worst example you could have chosen to support your statement. Making it close to illegal to be homeless is wrong, and a treatment of symptoms not the illness. Besides which, secondhand smoke is not something that just lurks around waiting to jump into some kids lungs. Smoke settles. What makes it a problem is when someone smokes inside, or when they smoke right next to someone that doesn’t want to smoke. That is called being an asshole.
Secondhand smoke is an issue of responsibility. If people can be taught to drink responsibly, then people can be taught to smoke responsibly.