It pertains because... take a family that lives in for example Hickory Hills. That family already made up their mind up that the public school in that area is not what they are looking for in education. Could be a number of reasons. In this case, the public school in that area already lost that family. Now, for that family, the only question that remains is which catholic school? Marist, Providence, St. Laurence, Mother McCauley.
That is why it is important to ask why would a family have their child travel further just to go to the Cathoic school while still paying taxes for the local public schools.