There's always someone who has to chime in and say "Why track your teen?"
That's a personal choice up to each parent.
It's convenient for us to see where our son is. With marching band, they would have competitions at the other side of town so it was nice to know they arrived safely and see when he was on the way back to school so we could pick him up, usually late at night. When he traveled out of state with the band to be in a parade we drove separately to see the parade and were able to locate him to say hi easily in crowded downtown San Diego. He would have never been able to describe where he was. And on the way home from San Diego we could see the bus was on the way home much earlier than were and arrange for him to get picked up at school by a family member since we were running a few hours behind them.
It's not bad to want to know where your kid is