Valid point...there is a lot of necessary subjectivity in officiating. Still, to use your example--I think we both agree that a push in the back is not considered legal contact according to the rules/laws of the game (depending on NFHS or FIFA rulebooks, respectively). How much force is necessary for a push in the back to become a foul? According to the rules, any amount should suffice, if the act is committed with intent...the relative strength exerted does not change the decision to commit the action.
The question is, then, how much force is necessary to make the difference between a foul that should be whistled and a foul that should fall under "let 'em play" to avoid "trifling" or taking advantage away from the team that is fouled but continues their attack nonetheless?
So back to what I mean by "calling it wrong," using your example.
Player A is dribbling down the sideline. Defender B, knowing she is beaten, pushes A from behind. A stumbles but retains possession and continues the attack. There is no whistle. I'd consider that calling it right--the illegal contact did not significantly affect the play of the game.
Player A is dribbling down the sideline. Defender B pushes her from behind, causing her to lose control of the ball, which goes out of bounds and is awarded to Team B. No whistle. In this case, the illegal contact caused a change of possession and an advantage for the team that committed it, but the referee decides that a little shove in the back is all part of the game..."rubbin's racin'", if I can quote Days of Thunder. I consider that "calling it wrong," not only because it creates a temporary advantage for the team committing the foul, but letting that kind of contact go, and CONSISTENTLY letting it go, as you advocate (I mean, if you didn't call it 5 minutes ago, you're not going to call it now, right?) usually results in encouraging players to try rougher and rougher play more and more often to see how much they can get away with.
So I'll respond to your question with a question in kind...how many times do you let a player commit a marginal infraction without feeling like they are testing you? How far do you let marginal behavior go before it degenerates into hazardous behavior? How many pushes in the back does a team have to commit before it becomes a pattern rather than an incident, and at what point do you break the precedent of not calling the first one and get control of the pattern?
What if you (perish the thought) actually make a mistake, either with a call or a no-call, realize the mistake was made, and then are faced with the same type of situation minutes later? Do you again make the same call or no-call, just because you did it a few minutes ago and even though you realized it may not have been the best one?
Emerson once said, "A foolish consistency is the hobgoblin of little minds." Not recognizing developing patterns and changes in the temperament of the game and adjusting your reactions to fit would seem to fall into that category.
