The fact that child protection fobbed you off would be enough for most people to understand this isn't something they are concerned about. I know of a couple of cases where they were contacted and had an inspector on-site within 30 minutes, so this isn't a case of them not addressing an are of concern, it's more likely someone just trying to politely get you off the phone so they can deal with the real problems.
Excellent, now show me where they say children selling raffle tickets is a problem? What I've seen all points to exposure to lottery type gambling which involves odds based on the prediction of future events is where the real problem is once combined with a poor grasp of maths and a misplaced confidence in their ability to predict the future.
All children should be exposed to the detailed workings of raffles. It would aid in learning probability and likely ensure fewer end up with gambling problems. The earlier they learn the house always wins the better.