When I turned 18 I bought a pack of smokes simply because it was a new thing that I was now allowed to do. If there was no age restrictions against buying cigarettes, people wouldn't be compelled to buy cigarettes once they become of age. Removing the age requirements on the purchasing of tobacco may seem like a bizarre proposition, but in many countries it is not illegal for children to smoke; it is only illegal for children to buy them. Wouldn't it be much better to make it illegal for children to smoke but not illegal for them to buy smokes? This way children could buy cigarettes for their parents if their parents send them down the shops. This action would waylay the child's curiosity so that when they do become of age, buying cigarettes would no longer seem glamorous, and as a corollary, it would lesson the likelihood of young adults taking up smoking. Making smoking illegal for underage children would net revenue through police fines, which the child's parent or guardian would have to pay. This would put more responsibility on the parent to become a good role model and, perhaps, give up smoking.
The argument isn't about if cigarettes are bad or not, but whether the age restrictions make smoking more attractive to underage people. When I was in school many students smoked because it was cool. I wonder if the fact that they were too young to smoke was a major contributer for them to start smoking. At the same time it was not technically illegal for them to smoke and so teachers did nothing to stop them from smoking at school. It seems that the government wants underage people to smoke by making it a cool thing to do. If there was no age limit to buy smokes then it may not seem so cool. Why not make it illegal for under 18s to smoke, but not illegal to buy them?