I cannot understate how much I hate this, despite not smoking, because it violates our most important rule: before the law everybody is equal. We except children, for obvious reasons, but with the promise that when they get a certain age they get the same right as anybody else.
You have to show ID to purchase tobacco products. They even have signs at some convenience stores which say the year you must be born to purchase tobacco products, which the year is the current year minus 18.
Stop changing the cutoff year. This will allow the current generation of tobacco users to continue, but ban future generations from it.