I will leave mine in the car to duck in and pay for petrol but that is only if my DD who is the oldest is in the car to press the lock button to lock and unlock the car and I only live in a small town and the car is always in my line of vision. There is no way I would leave them in a unlocked car with the keys still in the ignition and go into the shops! I wont even put bub in the car when I take the trolley back, he comes with me. I am glad the little one is ok and that the sister was able raise alarm but it baffles me how a parent can let it happen. Sorry if I sound judgemental and offend anyone but that is just my opinion.