I think Garner's point is that we live in a society in which other people's regard for your worth is a function of your age.
She is typical of "me me me" and the continual flow of sexism we see from Australian journalists. The last few decades in Australian media have been a dark spot. This author is sexist, arrogant and takes pride in yanking a strange girl's hair (which is tantamount to assault).
"In two strides I was behind the schoolgirl. I reached up, seized her ponytail at the roots and gave it a sharp downward yank."
"My only regret is that I couldn’t see the Asian woman’s face at the moment the schoolgirl’s head jerked back and her insolent grin turned into a rictus."
"The armed child behind the police station counter unable to conceal her boredom...."
How we are regarded is largely a function of how we allow ourselves to be regarded. Rejecting other people's regard when it is based on faulty premises is one of the gifts of age, that, sadly, not everyone acquires.
Self regard is the cure for the disregard of others.