Ok, now that I have your attention…
Nissan has a test program in Japan that is placing receivers in cars to alert drivers when children wearing special RFID/WiFi bracelets are in the area. This is supposedly for the protection of the children. [here]
Do you see a few problems with this, mainly due to the naivete of the implementation?
Pedophiles can’t live near schools or parks, or other places where children gather. Now they will not be able to buy Nissan vehicles, for it could be used as a hunting rather than tracking tool.
The tracking bracelet idea sounds good on paper, but it is extremely naive, and likely will never appear in the US, or any other half-sane nation.