Reason: Generally, children who have no common knowledge of religion will destroy the quiet atmosphere of religious places and have disrespect in it. Superstition says that children who don't know the rules and bump into God may be bad for them.
In addition, on the issue of drawing lots, children are generally not allowed to draw lots, because in principle, it is good for adults to be good to children. Generally, it is ok for children to draw lots for their studies after high school, that is, after 12 years old.