It makes perfect sense when you consider the political version of the "Golden Rule" - "He who has the Gold, makes the Rules". The "other" substance has a lot more money (and thus, political influence) backing it. It also has the backing of many very visible, vocal, influential people such as film/music celebrities, who have the ability to use their fame as a platform for their thoughts.
Our health and/or safety is not an issue. It's never an issue when decisions like this are being made - it's all about who's lining whose pockets with money. There's a lot of noise being made about the flavors in e-juice, yet nobody's talking about the many flavors of hard alcohol you can readily buy in any grocery store. Cookies & cream vodka, cherry whiskey, coconut rum, etc. Why not? Because the alcohol industry has untold billions of dollars behind it to buy off politicians/government entities and make sure their status is never threatened. Couple that with the fact that they also have massive public support and the government makes lots and lots of money off the "sin taxes" on alcohol, and you can be virtually guaranteed that nobody will ever bring up even the remotest possibility that flavored alcohols encourage teen drinking.
Follow the money.