KFC did not do its research well. Bitcoin is has very tx fees, and bitcoiners would not likely to use bitcoins for this small transactions. KFC should accept ETH or other altcoins instead. 
With just small transactions it is hard for us to make transaction when we are buying kfc or other fast food chains, I think it is not practical nowadays and the cost of the blockchain fee is really breaking our heart, but they can make bitcoin as their company's investment but not for daily transactions.