So you are complaining about the lack of traffic signals, not the roundabout.
The issue is that roundabouts generally only have a yield sign, which means cars are rarely at a standstill. This complicates pedestrians crossing the street.
Those seem to be an American thing? They aren't really in use in Germany.
And, in practice, people don't stop at stop signs. So this wouldn't help the original commentor's child survive.