This whole malleability fiasco has shown once again that zero confirmation transactions can not be trusted.
since its not practical waiting for 10 minutes for a payment to clear when buying coffee it seems to me that bitcoin will never go mainstream in physical shops.
any solution involving a third party to clear payments defeats the whole purpose of bitcoin.
any third party will effectively turn into a bank along with all the classical fractional reserve practices we have today.
nah, if I own a large stake in btc and have a chain of convenience stores I would always allow my customers to buy with btc as long as I know who my customer is.
I'm not insulting my customer over a $5 cup of coffee if I see the payment I wait for the confirmations, if the confirmation never arrrive when the customer returns we discuss it. Everyone that has anything to do with btc SHOULD know that it is not perfect.