To get CCB your child must be immunised, that's just how it works. CCB is childcare benefit, perhaps your friends don't use childcare.
And just to clarify, to get CCB, your child must either be immunised, exempt from immunisation, or have a conscientious objection. Immunisation is not compulsory to receive CCB, as long as you've discussed it with your GP / Paediatrician and signed the appropriate form. Same for the immunisation allowance.