On FT, this seems to stem primarily from TED's refusal to serve a full can of soda.
(OK, so absence of first class, etc. might be in the mix as well ).

In contrast, on a mainline SNA-DEN flight today one of my seatmates asked for sparkling water, and then as the FA attempted to hand her the can she said "Oh, I don't want the can."

Fortunately, I was not drinking my own beverage at the time, and thus the otherwise inevitable spit-take was avoided.