I have a problem with the parents suggesting that their child died because of other parents that sent their sick kids to school.  While that likely was the cause as to how she was infected, it's extremely difficult to be a parent with kids in any sort of school right now.
Fact of the matter is kids get sick...constantly.  Also most kids with Delta have runny noses and coughs, basically the two most common symptoms of any virus.  So the options are to test your child every time they have a runny nose and/or cough, which is probably the right thing to do in this environment, but also not ideal or realistic to most Americans.
We had a situation at my son's school during the height of Delta here in Florida, where a mom was not feeling well and dropped her kids off at school fully knowing that after she dropped them off, she was going to get a covid test.  The mom tested positive, waited till after school was finished to pick up the kids and then took both of them to get tested too.  Both kids also tested positive.  In this situation, the parent acted selfishly and their behavior was extremely reckless.  But if your child hasn't been around other sick friends/family members or wasn't knowingly exposed to someone that has tested positive for Covid, it's hard to blame parents that send their kid to school with a runny nose/cough and ultimately not knowing that the child may have Covid.  JMHO.