I'm on the "it can happen " side of the argument because it happened to me. I was on Ischia passing through the pool area with my 2-year-old on our way inside and ran into a friend. We started to chat and my daughter went over to the edge of the pool and crouched down to put her hand in the water. I was watching her like a hawk the entire time. She tried to scoot forward to get closer and the toe of her flip-flop caught, sending her head first into the water in the 1m end of the pool. She sank like a stone. I could have won an Olympic gold medal in the long jump with the distance I cleared. I got her before she reached bottom. She was a little shocked but otherwise fine. We went and took a nap. My wife came back to find all my clothes, wallet, money, etc... laid out and still wet. She said she instantly thought, "I can't wait to hear this story".
If you're a parent the odds are good you're going to have a near miss or two along the way. I was on alert the whole time and I think Andre was too. If you're going to have your kid around water and not watch at all, that is negligent but in this case (and mine) adults were close by and watching.