Unfortunately, I think its just a matter of behavioral training. I *never* touch any chests above small (which are never trapped) if there is a scout in the group. By default, they are the assigned disarmer/opener by sort of unspoken rule.
It's more of an issue in pick-up groups, but the scouts usually get it after being asked to disarm/open. Or, even just disarming is fine. Woe betide the scout that doesn't disarm boxes
