Ultimately stats show that kids under 5 (and especially around 2-3) get squashed at a much higher rate than kids that are tall enough to be seen out the back window. Rear view cameras are a tool and I highly recommend using that tool as an added tool in your toolbox.

For these two scenarios (1.short kids and 2. can't see shit when backing out of a park), the alternative is to drive back slowly and hope.