Also, why would they carry the keys with them? Why go to all the trouble of burning everything, and yet you carry the keys? Was it so they could lock the doors before they torched it?

I doubt carrying them would be an oversight. If they were on the run and using a stolen vehicle, knowing where the keys were at all times would be very important. If you lost them, you'd have to steal another car. So wouldn't forget they had them.[/QUOTE
If the keys were to the burnt truck, they could have kept them because they also had their house keys etc on them, intending to use later. Then when burning the RAV4 if by then they felt they had nothing left to live for, no longer needed them and dropped them. That could also explain why they didn;t take items that would be invaluable for survival out there at the time. If you are intending on continuing on in life, they could be valuable, if you are intending on dying, of no value?