So you just pull out your phone at payment point of shopping, click once on it and its done.
Thats how it should go.
Well this is all about convenience and I agree with you if the people are just going to use bitcoin then that is going to have an easy transaction if they are going to use it. And base on my experience this is really a good way to invest at all if you don't want to do some efforts then you can just leave your bitcoin to your wallet address and grow itself.
I don't think that groceries will start accepting bitcoin as a payment method especially in poor countries where grocery owners are illiterate and have no idea of how to handle new technology.