They were not able to recognize them as kids rather than generic humans. Kids behave differently and more erratically.
The details are not that imporant. The main point is that they were aware they were couldn't match human performance on kid safety yet still put their cars on the street. all while talking about the terrible toll of car crashes on children.
> Two months ago, Kyle Vogt, the chief executive of Cruise, choked up as he recounted how a driver had killed a 4-year-old girl in a stroller at a San Francisco intersection. “It barely made the news,” he said, pausing to collect himself. “Sorry. I get emotional.”
https://www.nytimes.com/2023/11/03/technology/cruise-general...