I think it is awful. It is scary how normal it has become.
I do worry at times when my older teenage son is out clubbing. There would maybe be some sense of security to be able to track that he is still in the club, or on the way home in a taxi, but I know that this is not fair to him, and safety behaviours like this are rarely good for managing anxiety.
It's all well and good to say your teen can just turn it off, but they are not going to want to alert you to the fact that they don't want to be tracked. That is likely to come with a few questions!
I do not want to teach my children that it is OK to be tracked for their 'safety', or other people's convience. It really isnt OK.
I also wonder how many teens freely consent to being tracked, and how many go along with it to keep the peace, or because their parent's anxiety has rubbed off onto them and they now feel unsafe without it.
If my husband wanted to track me so he knew when to put dinner on, I would wonder what the heck is going on with him. A text message has always sufficed if he really needs to know where I am for some reason.