The vast majority of children we work with where DOLs are in use or being applied for, or where secure is being sought is not for grooming and exploitation, its for what we would consider MH issues (self harm, suicide attempts) but CAMHS do not consider a MH issue so they're not involved with the child at all.
In addition, where there is a high level of anti social behaviour, attacks on staff, the public, self harm, public disturbances, the criminal courts expect that children are accommodated in 'secure settings' without actually having any understanding about what the legal thresholds for that is. Often a child is in court being heard for those issues and courts expect the child can be detained in secure right there and then. A DOLs or trying to re create a secure setting within the community just doesnt work. Residential services are not set up to 'police' children in this manner
Equally, if it was stipulated that male workers dont work with female children, there would be even fewer placements available.
And yes, the prices quoted above for these types of placements are not unusual, we're working with this day in day out, its why local authorities are going bankrupt.