Privacy issues could be circumvented if you tie the tag to a government ID instead of an individual.
Whether a person needs a device to assistance them in seeing or hearing is a health condition and is protected under their right to privacy.
Yet in order to have the privilege to drive an individual must forfeit that RIGHT to privacy and allow a notation on his driver license for all to see that reviews that license for ID purposes or traffic stops.
If a person has a physical handicap, something else that is protected by his/her right to privacy, he/she must give up that right of privacy and publicly display a sticker tell all that he/she has a handicap in order to use special parking.
A person has a right to privacy regarding how old they are but they most give up that right if they want to purchase certain privilege items (Tobacco, cannabis, alcohol, sudafed) or obtain certain age restricted discounts.
You posted about a right (privacy) and conflated with with a privilege (driving).