As the other child comment mentioned, there are many ways to identify yourself to a store that don't require facial recognition. The YMCA for example has a system that lets users track their exercise history; there's no reason Macy's couldn't do the same for your purchases. If indiscriminate ID'ing is the default position, then you have decided that _your convenience is more important than the freedom of every other person in the store._ It should be the responsibility of the person who wants this convenience to opt in, not the responsibility of the rest of us to opt out.
The desire to not have PiD stored by anyone should be reason enough to close the debate. But if it's not, we fortunately have hundreds (thousands?) of cases of corporate consumer abuse and irresponsible data storage to point to.