They're also pricks and idiots for not realizing that even if their kid catches something and "is just fine!!!!!", that kid could and like as not will pass it on to someone who can't fight it off. That someone could be their friend who's undergoing chemo, it could be their preemie baby brother, it could be their great-grandma Gertrude. I remember a massive fight between two high school friends, one with a compromised immune system and one with no understanding of what a vaccine is. She legitimately thought vaccines were like herbicides in that they'd kill whatever they touched and "just so happened" to mostly kill "bad cells". Our bio teacher smacked her with the Cluebat of Great Justice, but not before answering a hundred stupid questions and facepalming a bunch of times. Homeschooling is a hell of a drug*.
*before anyone jumps down my throat, I was homeschooled for eight years. This is self-deprecating humor.