That's partially correct, in my opinion. Children do have access to cigarettes in the face of regulation. But without any restrictions, child smoking might be out of control like this: VICE on HBO Season One: Addiction (Episode 7) - YouTube
I dont think age restrictions is a perfect measure, but it's better than no restrictions/regulations.
What would be best is if underaged people could get e-cigs by prescription from their doctor, even if it was for the limited purpose of NRT -- which would at least cover young people who want to stop smoking, until they are of age. I started smoking when I was 13, and my parents knew it by the time I was 15, and though they didn't condone it, they were both smokers who understood that it was an addiction, so they put up with it, but if something like e-cigs had been available, I feel quite sure they would have insisted on it, rather than on merely switching to "Lights," from full-flavor.
Andria