Regardless, the larger point is that Starbucks benefits from reduced fees when people make fewer but larger credit card transactions, so there’s a push to have people reload accounts with Starbucks funny money rather than make separate credit card purchases for each order (putting the “bucks” in Starbucks!).
I actually think this is more about the float than the credit card fees. (Starbucks is large enough to negotiate those fees down, and probably pays the same fees when I reload my card from a credit card as when I directly make a purchase.) Starbucks has over $1bn sitting on gift cards, money that they don't pay interest on (though they do pay double stars, for whatever those are worth), but that they most certainly earn interest on.