It has to be in the judgment of the referee if danger is actually being caused to anyone.
Traditionally in High School refs have automatically called it if a player attempts to play the ball whilst on the ground. But if you read closely this is not mentioned specifically in that way. In the part of the book which deals with specific situations it states that the ref should decide if it constitutes a danger. If it does not then it should not be called.
In High School everyone shouts for it the minute it is done but it is not always a dangerous play.
Similarly with high kicks. It has to constitute danger to be called, but again everyone shouts for it all the time. If a player goes for a high kick with no-one around him then it should not be called.
