Why is Rush so Cut-throat on the Sororities' End at Big Greek Schools?

[bamabelle005]

the old row sororities are alpha gamma delta, kappa delta, delta delta delta, chi omega, phi mu, alpha chi omega, and kappa kappa gamma. and for the guys it is kappa alpha, sigma alpha epsilon, delta kappa epsilon, phi gamma delta, phi delta theta, sigma nu. "old row" just means those people pay more $ for more parties within the "old row" group; and old row isn't always the first 6 or 7 sororities and fraternities