You have no idea what they witnessed. Only what the mom said. And she is not a neutral party. Why not give the callers the benefit of the doubt that they were concerned and did what they thought was in the interest of the safety of a child.
As I mentioned previously, I am a parent of two kids on the autism spectrum (Asperger's). I know the difficulties faced by parents of children with full-blown autism due to social interactions. I also know that people who have never dealt with autism know NOTHING about dealing with those who have it. Five minutes of watching would've shown those busy-body bystanders that the family was not abusing their kids.
Five minutes. That's all. Instead they decided they knew what was best for the kids after 10 secs, and called the cops.
You ask me to give them the benefit of the doubt, yet you require no such thing from them? This is why I have the attitude I have.