I was a JW for forty years and in that time I was asigned to work alone on field service with other members of the congregation in rural settings regularly my mother never went on field service at the weekend and my father was not in the organisation. I was encouraged to study alone with another congregation member to "help make the truth my own". I attended study groups specifically for children held in private homes (it later turned out the father was molesting his daughters). JWs do on occasion separate children and parents and therefore they should have CRB checks done. After all for charities it is free to do and if there is nothing to hide there is nothing to fear. The Watchtower encourages mature christians to help out spiritual widows and provide role models by studying with children on their own.
They say they are more moral, and have higher standards because they are in a spiritual paradise so to comply with a law shows good faith and reinforces their high standards.
This fudging the issue and falsehood by stating that because there are no Sunday schools it is all ok is a fallacy. Things are not ok. Children have been molested by brothers they trusted, children have been molested on field service, children have been molested in kingdom halls. The purpose of the rules is not to persecute the innocent but to make it harder for the wicked. The present culture and rules DO NOT WORK. They have never worked except to protect the reputation of the society. The checks won't catch everyone but they will help.