As far as I can determine, every State of the union has either a magnetic stripe, or a barcode, or both on the back of your driver's license in America. Ostensibly, this is done so as to provide a service to the police when you have been pulled over or are being questioned, so that they can simply swipe your driver's license or scan your barcode to ascertain quickly whether there is anything about your identity that would necessitate them taking a more meaningful action against you or in theory, to protect and serve you.
First off, what exactly is contained on your driver's license barcode or magnetic code? Essentially what is contained is in digital format all of the pertinent information on the front of your driver's license with the exception of your actual picture and because this information has been scanned, any company or person utilizing equipment that can scan your license will also have the capability of storing or maintaining this information too, whether they are legally entitled to it or not. In some States, there are laws that preclude companies or individuals from doing so, but in some States there are not.
The next logical question is why any company or individual would actually need to scan your license when the information that they are looking for is clearly in their view, right in front of their eyes. While you can make a somewhat weak argument that the license needs to be scanned to cut down on "fake IDs" or as easy way to verify the age of someone buying liquor for employees that are incapable of figuring out your age based on your birth date, the real reason can only be for their own marketing, targeting, or nefarious purposes.
Now let's go back to the ostensible reason for barcodes or magnetic stripes in the first place which is for the ease of use for police or other civil authorities. The bottom line is a barcode or magnetic strip isn't necessary for law enforcement, because each driver's license, just as each passport, or each social security number, is unique in of itself, with its own individual identifying number. Folks, it just isn't that complicated to type in a number, verify it against the driver's license, and then read your screen to see if there is any actionable information on it.
What is really happening here is that your driver's license is becoming more and more like a national ID card in which your personal activities can be monitored and tracked not only by government and civil authorities but also by stores or organizations that you have to frequent as a matter of course. It is one thing to make this type of tracking, voluntary, by your use of a loyalty card, or a membership card, and it's another thing entirely to make it compulsory.
In short, people have a right to be left alone, people have a right to privacy, people have a right of discretion, people have a right to not have to live their lives inside a fishbowl, and people have a right to not be monitored, they need to be able to have a sanctuary.