That’s just not true — consequences for not having their children vaccinated are legislated lots of places; the arguments against anti-vaxers are often appeals to the same authorities that happily over-prescribed opiates and based around shaming them; etc.
I'm talking about what people say, not what they do with their children.
But can you be more specific? What consequences can you name, especially in the US? I'm not aware of there being almost anything in the US, except that they might not be allowed into some schools, which barely even counts as a punishment.
I do hope you realize that people being anti-vaccine can and does result in the deaths of completely innocent parties.
The consequences for people not vaccinating their kids goes beyond just belief. Even then in America we're incredibly lax on those people despite the fact that it seems to be growing movement fueled by quackery.