There are certain costs to a field that are only a consideration of magnitude. Let me try to explain through example:
Fields run best when there is a certain player to ref ratio. Some insurance policies require one. Lets just say its 10 to 1.
A field generally overstaffs this ratio.... again I need to back up and rephrase. Successful businesses generally overstaff this ratio especially when discussing businesses seeking disposable income because the experience is more important than price (within reason). IE you might put up with Wal-mart and buy that tv there to save $25. You will not put up with bad service at a field if you could have a good experience for $25 more.
So fields are generally overstaffed. Unless you are operating at peak capacity to this ratio, or at peak overall capacity, you have unused entrance.
Don't lose out on sales of other items (ie paint, chips, hot dogs, soda) that have good mark up because of your entrance. You are better off giving entrance away if that is what you need to do to get the optimal number of players there. This is especially true when dealing with a business where the other customers provide atmosphere for paying customers (its a base concept behind "lady's night" at the club).
"In the essentials: unity; in the non-essentials: liberty; in all things: love" - often incorrectly attributed to Augustine or John Wesley - original source in question
"Use peaceful means where they are appropriate; but where they are not appropriate, do not hesitate to resort to more forceful - Thupten Gyatso (the Dalai Lama, 1932)
"It is not the will to win that matters - everyone has that. It's the will to prepare to win that matters" Coach Paul 'Bear' Bryant.
"The ink of scholars is more precious than the blood of martyrs" - Muhammed