Hey Tony, you are not being very discreet with this question, your English is better than this!
To answer your question, it is difficult for social services to monitor all situations when the parents themselves will not, or afraid to admit that abuse is taking place.
In the majority of cases excuses are made by one parent or another to cover abuse.
I am not a supporter of the present regime of 'take the child into care' policy, but the prevailing liberal PC attitude towards child welfare is biased towards the 'family' environment rather than the prime directive of the 'children's welfare comes first'.