You don't need a globally recorded block chain transaction to buy things in your supermarket. If the supermarket screws you over, you go to a different one. Until then, you just trust them they don't steal a bag of food's worth from you.

Such things can be handled by cheap payment processors, and if you're paranoid some block chain escrow to keep it from running with its user accounts. It's a complete waste of bandwidth and storage to do the single transactions on the block chain.