I am fine with people (especially if they are licensed professionals) reading my private conversations and photos, but I worry about people (especially licensed law enforcement) accessing my data on online child abuse.

We can not always get what we want.

Instead, we entrust the police a monopoly on violence, physical detainment, and violation of privacy, and hold them accountable if they can be shown to disregard their duty and responsibilities. As a civilian, your duty is to weigh your personal sense of discomfort against the societal benefits of improved child abuse detection.