when they put surgeon general's warnings on boxes it hardly made a difference.

It made a huge difference. But its also because before that, companies were promoting tobacco was "safe" and even "beneficial". So an explicit warning would been a suprised to most people of that era. Did it stopped addicts? No... but the next generation was more weary before beoming addicted. But yeah, i dont think a warming today would have nearly the same effect as that information is far more widely available