Final answer:
The difference between vertical and horizontal driver's licenses lies in the age and presumed legal privileges of the holder, with vertical licenses usually indicating underaged individuals and horizontal licenses signifying those of or over the legal drinking age.
Step-by-step explanation:
The distinction between a vertical and horizontal driver's license primarily indicates the age of the holder. In many states, a vertical driver's license is issued to underage drivers, typically those under the age of 21, signaling to others, such as law enforcement and alcohol vendors, that the holder is not of legal drinking age.
On the other hand, a horizontal driver's license is usually issued to drivers who are 21 or older, illustrating that they are of legal age to purchase alcohol. This design difference is an example of how government engages in legal discrimination based on age, serving to enforce laws related to age-specific activities.
Such discrimination is legitimate as it is intended to promote safety and public welfare. Similarly, governments can also set standards for admission to public colleges and universities based on academic achievement as this is seen as a means to ensure a certain level of educational attainment and readiness for college-level work.
These forms of legal discrimination are allowable because they serve a specific, rational purpose and are not arbitrary, which is in line with the equal protection clause that aims to prevent unjust or prejudicial treatment among different categories of people.