Utterly false equivalent. You're actually trying to equate a scientific measurement with a loose concept of language. That's absurd. A scientific measure is fixed; language is not.
No one commits a violation of anything by addressing an eight-year-old boy as "young man". It's figurative. Get over it already.
The measure of a BAC is rather exacting, however its INFLUENCE on a person VERY variable. the standards were set based upon emperical observations of a wide range of people.
So me at .12 may be more functional than someone at .06, however for it to work legally a standard must be made to allow comparison to the easily obtained value (a BAC) and not the arbitrary observations of a law enforcement officer that "someone is drunk" this is then codified as over X BAC is impaired, and you are criminally liable.
In the case of majority, yes some people mature faster than others, but unless we test people every year to see when they become an "adult" a standard must be applied. The issue isnt the language, its the fact that the laws want minors to have EITHER a persecription or parental permission to obtain morning after pills, and some idiot judge thinks this is a bad idea.