My DM took my DS (20 months) out for the afternoon. My DH went out to meet DM and DS at the gate when she brought him back. She was walking about two steps ahead of DS on the pavement and was not holding his hand, whilst he followed her. She was also looking around saying hello to our next door neighbour.
We live next to a road which is not particularly busy, but it has through traffic and people drive very fast down it. After speaking to her, she said we shouldn't worry as she was "in control".
I throw myself at the mercy of AIBU as I am bloody fuming!