cigarette sales vs alcohol sales

I find it odd that in order to buy cigarettes, you need to be 18 or over and you can buy them at the supermarket where a 15 year old can sell them to you.  Too young to smoke, yet not too young to sell them and make sure the people buying them are over 18.

However, in order to buy alcohol, you need to be 18 or over, you walk into the store (or supermarket in some cases) and you can only be sold alcohol by someone who's over 18 too.

Really, what's the difference?  If it wasn't ridiculous to be insulted to be sold cigarettes and have ID checked by a 15 year old, I reckon I'd be insulted at that concept.  I guess I'd need to want to go buy cigarettes too huh :)