So the kids need to figure out that in order to do this kind of thing they need to attach their watch to some less-cool kid's wrist that stays at school while they do the fun things. At least that less-cool kid hopefully gets some kind of reimbursement for offering that service.

They don’t have to sit at school, and they can wander around, without telling me — but if there is a serious trouble then it’s in everyone’s interest to have a up to date location data.

Are you kidding me? I remember being a teenager in the 90s. I had a great relationship with my parents (not perfect, of course, but who does?), and I absolutely would not have wanted them to have my exact location on-demand. I didn't get up to all that much that they didn't want me to do, but being tracked would mean I would not have done those things, and would have missed out on valuable experiences, because I would have been afraid that they'd randomly check up on me when I was in a place I wasn't supposed to be. (And no, I'm not talking about drinking or drugs or anything like that.)