How would you answer your kids?

My 8 yo was asking yesterday why we can ban chewing gum but not cigarettes.

I was contemplating in my mind for 30 sec whether to tell her some bs that it's not simple to implement the ban, and continue letting her live in her wonderland.

OR just tell her the ugly truth...

In the end I decided to the her the truth.

What would you do in your case? Will you typically paint a beautiful picture to hide flaws? Or just tell them the ugly truth?