I also carry a SPOT.  One never knows when they will have a serious problem to be rescued from.  My family and friends like to watch my progress with the tracking feature and it reassures them, and me, of a way to call for help when solo paddling.
"Hope for the best but be prepared for the worst" is good advice.  That requires quite a bit of forethought and planning and carrying some extraneous stuff you might never use.  Newbies to canoe camping, not thinking of being DAYS from supplies or help, might not take many standard items which could be needed in a pinch.
Regarding losing a canoe  :o :o :o THAT would be awful.  I never get out of arm's reach of my boat without making sure it is tied to something.  If I did lose my boat I would first see if I could walk to it by taking the shoreline.  If on a known canoe route I could wait a day or two to see if someone else would happen by and help me locate the boat.  Once I used up all my food I guess I would have to hit the panic button.