We can go on and on and on about this subject and never get anywhere. So let me just lay it out:
At some schools the student population and particularly the Greek population is very traditional...18-22, students rush the first semester or don't join at all, everyone lives in the house.
At other schools the student population is majority commuter, lots of returning students, age 18-80, upperclassmen often go Greek, there IS no house.
If you go to a type A school you probably won't give a married or pregnant (married or unmarried) woman a bid unless hell freezes over.
If you go to type B school it's not as big of a deal. Mainly because the majority of your sisters probably aren't "typical" either.
Students at very traditional campuses have to realize and understand that there is Greek life outside the parameters on their campus...just as students at very nontraditional campuses need to understand the importance of matching outfits for rush.
Who goes to college and when is changing more and more every day...either Greek orgs need to change with it or they can become resigned to a progressively narrower scope.