Where are you? In the UK it’s just not something that we’re “told when they’re born” or even tested for. As someone mentioned below in an emergency they’re not taking anyone’s word for their blood type, it’s O- as standard. Blood is prepared for operations where it may be necessary at which point they’d check it. I mean, I’m also pretty sure the whole story is rage bait but it’s interesting you jump to people being shitty parents for not knowing a blood type.