Why are 19 year olds still considered teens?

Where I live 19 year olds are considered adults in every way. Move to Australia..

it's in the name. nineTEEN. idiot. 

and just because someone is 19, doesn't mean they have a job or are independent. these days, it's quite the opposite. 

Because they are nineTEEN, however, they do become adults at 18-years of age.

Not all 19 years have jobs, nor are they independent. Some are still in high school, in fact, while others are attending college full time and either not working at all, or only working part time while they're in school. So it makes sense.

A teenager, or teen, is a young person whose age falls within the range from 13–19. They are called teenagers because their age number ends with "teen".

The number is nineTEEN so yes. 

Well they're not in their 20s and aren't preteens so there's that.  

nine teen...................

People don't all mature at the same rate in all pre-war. While prosecuters insist on charging 18-19 year olds as adults, many in their 20s could as well be charged as juveniles.

Also, after WW II, parents started clinging to to their offsprings' childhood, preserving the image of them being "teenagers" as long as possible rather than as the "young adults" they were commonly thought of pre-war.

Jeff Besos has 150 billion. Marc Fuckerberg 60 and ex Crack Dealer Jay Z 50 million. You are making up your own independence BS.