Hope the day has ended peacefully hazydays. Scarlet it is by no means unusual for a child to be removed on a PPO, as it is often the most expedient way to remove a child and as the Order only lasts 72 hours, that gives time for the social worker if necessary to make application for an EPO and then interim care orders until the final hearing, unless of course the child is returned home. This doesn't necessarily mean that the parents are more violent than those whose children are removed by social workers after being granted an EPO by a magistrate.
Often a PPO is used when a child is left alone at home and neighbours phone the police. The police will attend and if the child is alone, then they can use their powers under the Police Protection Act to remove a child to safety without having to get a court order.
Obviously natural parents are not going to admit to harming/neglecting their child, and will be angry when they are removed. In my experience this is only ever verbal anger and is usually directed at the social worker. I honestly haver never known a case where a social worker or foster carer has been physically assaulted by a natural parent. In the main these parents (as I'm sure you will know) are often young, emotionally immature, have no family support, have endured abuse/neglect themselves as children and are unable to put the child's needs before their own.
As I said in an earlier post through the 80's and before, all contact used to take place at the home of the foster carer, and only supervised in very extreme circumstances. Many foster carers struggled with this, mainly because the parents turned up late or didn't come at all, or gave the children loads of sweets and were a bit hostile to the carers, but were not violent in any way. Somehow this practice was ended and now most contact is at contact centres. I think this is probably better all round, both for carers and natural parents.