A thought:
Some day (probably today), someone’s going to do something stupid, negligent or just plain retarded, and SOMEBODY ELSE’S child will die.
What then?
Will “I forgot!” be a sufficient defense?
Will “She’s suffered enough” be a sufficient excuse?
You are confusing the general meaning of negligence with legal negligence. They aren’t the same.
Stupid, ignorant, forgetful, human error negligence is not the same as criminal willful negligence which is knowingly choosing to act or fail to act in a way that can reasonably be predicted to result in harm.
There is definitely a fine line in some cases. It’s a prosecutor’s job to determine that line before proceding with a prosecution and wasting resources on a trial with a strong possiblility of a not guilty verdict.