and when you go missing, no-one will have a clue where you are.
I choose to
always have someone (a responsible person, by the legal definition) know where I am, even in my plane. The difference is that I choose
who knows where I am,
not everyone knows where I am. When I select altitude on the Transponder, and having told my family, everyone who needs to know where I am, does. I don't like the idea that random computer users could track my private whereabouts.
I do agree though, that that is a privilege of
private flying. Once the flight is in any way compensated, the passenger should be entitled to suitable tracking, as they have purchased a transportation service, with expectations of public assistance, should it be needed. The public emergency services (whom we pay by taxes) should be able to accomplish their role with reasonable efficiency, meaning more rescue than search. If you've kept your location private even to emergency services, you have surrendered efficient (or even any) rescue. A pilot has no right to put a passenger in that situation.