Whenever you don't pay with physical cash(paper money) you are paying with an account - either charging to a store account or a debit account or a credit card account.
When you talk about a customer having an account with a retailer, that's not the same as a customer owning bitcoin. The account with a retailer is part of a "formal banking, brokerage, or business relationship established to provide for regular services, dealings, and other financial transactions" with that retailer. Bitcoin is more like cash. It's not a relationship with any one individual or institution. You might as well say dollars are an account you have with the American government and/or its people.
The emergence of Cryptocurrencies on the scene will not change this. You will still be paying from an "account" - it will just be a cryptocurrency account.
If you are saying I might have an account with my retailer that I settle in bitcoin, then I agree, but I suspect you are not saying that.
We will not see blockchain transactions at the point of sale on any kind of scale (e.g. large stores and supermarkets) where there is a high turnover of sales.
If they can take cash, and have an internet connection, they can take bitcoin. Bitcoin has many advantages over cash for the retailer and the customer. It has some caveats, but those can be managed. Loyalty cards and retail accounts will be layered on top of that, for those that find them convenient.