The Bitcoin protocol is designed to make it average 10 minutes between each block, so on average the wait is 5 minutes. And if I was Starbucks selling a coffee, I probably would be willing to accept zero-block transactions, especially if the user has one of those rewards cards. Just re-charge them next time around. Only very rarely will they need to eat the cost of a $4 coffee, in exchange for not paying 1%-2% on every single purchase.