triggers
People with poor verbal skills are perfect for abusers. Centres with very young kids, non verbal autistic people etc are often targeted. However particularly young children are difficult to have sex with because of the size of their genitals and anus.
There's also the elderly. An elderly person with dementia may not be able to give an account of what happened. They also may not be believed, you don't need to worry about them getting pregnant and they could die at any point. Elderly care is really badly managed.
Excellent point