I wonder if there was more to this case than we know about. I agree that I was surprised that someone could be prosecuted let alone sent to prison for what seems to be a momentary error of judgement/lack of safety knowledge. She said she didn't realise he could slip out of the baby seat. It also said that there were no other signs of neglect.
Lying about being on her phone is perfectly natural. You would have been feeling terrible and scared about being judged over what was in retrospect a stupid thing to do. She didn't lie about having left the room just why she had left the room. I don't see much problem with that.
I looked up the other cases of gross negligence manslaughter and the examples I read were much worse cases of negligence over time or really really obviously stupid things to do that could very obviously lead to and did result in someone's death. They tended to involve active decisions made instead of lapses of judgment.
That's why I wonder if there was more to it than we know or (and I hope not) that she received harsher treatment because if class and/or race discrimination.
Having said this, I do see a pattern of us starting to prosecute "accidents". A man the other day was convicted of careless driving (he was spared the higher penalty of dangerous driving and prison time) after he accidentally pressed the accelerator rather than the brake. Unfortunately this resulted in him running over two people who were killed. He was a pensioner who had just dropped off his wife at the hospital and had otherwise a clean record. The relatives of the deceased were very unhappy that he had "got away with it" (not sure if they actually said that but that was the gist). And I understand they are grieving and have lost loved ones so are angry and upset; but as a outside observer the whole thing sounded to me like a terrible accident.
I also wonder if he would have been treated more harshly (ie recd a harsher sentence or prison time) had he been a young working class man or woman or a black person? These people tend to be viewed very differently by the justice system and society than an elderly white person, and different assumptions made about their motivations.
There was another lady a while back who was prosecuted for forgetting to put her handbrake in when she stopped her car and unfortunately and very sadly killed her friend as the car started to roll as her friend got out. Awful and obviously we should do our utmost to not make such mistakes but things do happen to the best of us.
People are not robots we are fallible and we make mistakes and usually there are no awful consequences but sometimes there are. Punishing people for making mistakes isn't going to cause fewer mistakes so I'm not really sure what the point of it is. Other than to make us incredibly nervous (and probably make more mistakes as a result!).
Not sure I want to live in a society that criminalises people's mistakes. Even if those mistakes have terrible consequences.