In the 19th century, boys were recruited in their early teens, and sometimes younger. That is still the case in many countries (even if the United Nations set a minimum age for combat as 18).
Even in the US, the minimum driving age varies considerably. In rural areas, it is often much younger than 18, especially for driving farm vehicles. Insurance companies, based on driving records, charge tremendous amounts extra for younger drivers suggesting some evidence based reasons for a higher driving age.
Many countries have no drinking age. One should remember that the US is one of the few non-Muslim countries to ever make serious effort to ban alcoholic beverages. Given the stereotype of intoxicated college (and yeshiva) students, there appears to be justification for society’s concerns.
Of course, Bnei Torah generally have better things to do than play soldiers, never drink in excess except maybe on Purim (and not all that much then), and only need to drive to get to yeshiva or shopping — so this thread should be irrelevant to YWN readers.