My guess would be lateral/shear forces. Tall buildings are subject to a great deal of wind-related shear forces. If those forces lead to outward force being applied to sides of the foundation, then the ability of the ground surrounding the sides of the foundation to resist those forces matters.
Creative_username969 t1_j7n3spn wrote
Reply to comment by down_up__left_right in MTA spent twice as much on Second Ave subway consultants as it did on its construction by NYY657545
My guess would be lateral/shear forces. Tall buildings are subject to a great deal of wind-related shear forces. If those forces lead to outward force being applied to sides of the foundation, then the ability of the ground surrounding the sides of the foundation to resist those forces matters.