“As much as our dark roast coffee” isn’t an absolute value, but I think there really should be a sticker saying “Warning: high caffeine content / approx (x mg small) (y mg med) (390mg large)”. This sticker should appear clearly next to the menu items as well as on the cups. Self-serve stations should probably be removed since kids are vastly more likely to drink a ton of lemonade compared to hot, black coffee.
I drank a few of these not sure if it was “as much as a regular coffee” or “as much as an equivalent size.” I didn’t think twice because I take a lot of caffeine anyway, but I shouldn’t have had to google it.
I can see how depending on the circumstances of obtaining the drink, one might not know there is caffeine in it at all:
ordering from a third party online app that doesn’t have all the right names, descriptions, and pictures
ordering through a third party proxy or having the item described to you by a third party (“anyone want anything? They have lemonade…”)
There really should be a clear notice right on the thing you’re about to drink from, of exactly how much caffeine is in it. No marketing crap (“it’s charged!”) or vague comparisons (“as much as our coffee”) suffices.