Wait. Surely these aren't the same. My dad smoked and always told us he'd kick our ass if we started smoking. From as young as I can remember, I understood it was bad and that he was addicted, he had tried, and would continue to try to quit numerous times. He didn't often smoke in front of us when we were young. He passed away before my own kids were born. Emphphysema. At no stage in my life did I ever have any desire to smoke.
However, parents using their phone in front of their kids all the time. Well it's not obviously harming them, as far as the kids are concerned. There are also plenty of legitimate uses for technology. Kids can't discern between the two. Heck adults regularly can't.
Smoking by comparison is pretty freaking obviously a bad idea.