Of course not, but it can be done from the buyer end instead. Find a kid (any kid) who bought an ecig. Get their receipt and compare it to the records of the seller.[EDIT] Our House, I would love to see those stats... however, I would bet that no supplier is going to come forward and say "Yeah, we don't ID" or even "We fired Mr. Smith for selling a kit to a 12 year old". Are any suppliers keeping track of that kind of thing?
If they used a credit card online, the purchase was unauthorized/illegal, right? You have to be 18 to have a card. Plus, there's a paper trail. No such trail exists for grocery stores that sell analogs. Other than that, I'm not sure what kind of security measures can be put in place. I mean, you have to be 21 to play the lottery or bet horses and both of those are legally available online in the US.
If they bought it live, the fine an ecig vendor pays for selling to minors should be the same as the fine a grocery store owner pays for selling to minors. Why the whole industry should suffer for a small percentage of vendors is beyond me.
But the bottom line is that the people who are claiming sales to underage children have provided NOTHING at all to back up their speculations and assertions. They're just saying it...and this is why we have the "children facts" on our side and they don't. You're right, it IS a subjective argument. However the way it stands right now, it's only subjective for them, not us.