Most models out there are tall (5'10" or taller) and have 32 nearly 'a' cup..
Most clothes are made to fit these models.
Yeah; tell me about it. The petite department never has quite the variety as the rest of the store either. And have you ever looked at the "juniors?" Sheesh. Those clothes are made for stick figures with NO boobs. Where'd they ever get the idea that all teenage girls weigh 80 pounds and have no shape?