Diet Coke - Diet NOPE

I love to read the"behind the scenes" lists about airline travel and one particular fact from such a list sticks with me.  Flight attendants say their least favorite drink to serve in flight is diet coke.  Diet Coke takes up to 3 times longer to pour than other drinks due to its fizzy nature.

And there is a real reason behind it!  Regular coke is made with sugar which increases the surface tension and viscosity in the drink - and in real terms that means bigger bubbles are forming.  If you ever played with bubbles as a kid, think about how the larger bubbles floating in the air would burst first and the tiny little bubbles would be the last to burst.
This tiny air travel science lesson was all to say that I was surprised that on my United flight this week napkins were advertising Diet Coke specifically.  Not Coke, or Coke products, but Diet Coke, the bane of airline drink service.  What's up with that United?  It's not as if soda is a purchase item for passengers and choosing any other Coke product would be stealing profits.  Very strange.