IN that case the police didn't need any special surveillance powers. They were being approached by children who said "I am being repeatedly gang raped by men who have groomed me with money and drugs, and who are now selling me as a child prostitute"; and by sexual health clinics who were providing abortions and STI services to children; and by teachers; and by social workers.
Those police did nothing with that information.
It's a reasonable point: Why do they want these extra powers when they've failed to protect so many vulnerable children?