About 12 percent of American households earning less than $40,000 are unbanked, according to the Federal Reserve, and without a link to a bank account, Key presents a host of challenges. Among them is getting to one of the kiosks, mostly located at subway stops, that sell the cards and allow riders to load them using cash. Riders who primarily use buses may have no reason to travel near the Market-Frankford or Broad Street lines, and because the card readers on vehicles don't list a card's balance, they can find themselves unable to pay bus fare and nowhere near a place where they can add to a card with cash.