Really, come on people. The only reason they scan the ID is that the point of sale system takes the clerks guess work out of reading the ID and to insure that Target is following the law of who can purchase alcohol. When they scan the alcohol the POS system requires ID proof od age, before the clerk had to input the go/no go response. Then if the sale was not legal the manager had to suffer the wrath of a ticket. This way the clerk scans the alcohol, then scans the backside of the DL for a positive confirmation of a legal purchase.
I see no problems with this, most bars in the surrounding states have been doing this for years.
This. And really folks, there is no secret "algorithm". It is quite well known and widely used.