My middle son played rugby for a local club as a 'mini' starting with 2 years as an 'under 8' and going on until he was 13.  I used to feel the coach and refs were not hard enough on the high tackle. Maybe if they had explained why there is a high tackle rule, and taken action against it more often, the boys might have taken it more seriously. 

Apart from that, if the boys weren't going for each other on the pitch, they were probably fighting in the playground, as boys do. They were probably generally in less danger with the supervised contact sports than the unsupervised battles.