Yes, I do believe that they add a ton of stuff to make the cigarettes more addictive. When I moved up to Canada I started smoking a Canadian brand that was all natural. I only smoked a few cigarettes a day, maybe 10 or so. My cravings were not bad.
Then, I went back to the States and tried my old brand. Oh my gosh I couldn't even smoke them anymore they were so foul and chemically tasting compared to the Canadian ones. It was literally unbearable to smoke them. And these were ones I'd smoked for over a decade.
When I smoked the US brand I noticed that I smoked well over a pack a day. My cravings were SO much stronger. I smoked even when I didn't want to.