I can understand the argument concerning both chipping prisoners and the need to improve the justice system to avoid chipping those that are unjustly accused or unreasonably convicted.
As for the common person, the concern is not about the current tech, but the idea in general. A chip may one day be powerful enough for distance tracking and certainly sensors across all of America would make that distance a non-issue for tracking. And yes, there are many beneficial possibilities involving such chips, including the saving of lives. At the same time, there must be some means for the people to cast off said technologies for their own good. Believe it or not, any phone can be used to listen in on you at any time, even if it appears to be off. It's nothing new and one would be hard pressed to be certain (despite supposed legislation) that organizations such as the CIA do not use said methods.
I am not against technology, but prefer means which have fail safes against improper use. All technologies noted before (vehicle tracking, cell phones, etc.) have said fail safes in the forms of deactivation or abandonment. If a chip becomes voluntary, then I'm content.
Do keep in mind that the world is not safe. It never will be. There are dangers out there magnificent and mundane and we will get a bloody nose every so often venturing out into the world. If we can't handle it, we need to crawl back into bed. If we choose to brave it, it is all too tempting to sacrifice liberty for safety but such a sacrifice threatens to make cowards and, possibly worse, slaves of us all.