You basically need them to enforce pedestrian crossings.
I grew up in an older suburb that made judicious use of yield signs (give right-away to pedestrians AND vehicles). I remember being told as a kid to always give the right-of-way to cars and only cross when the intersection was clear - Smart advice from my parents, because cars had no issue zipping thru the intersection without slowing down while I stood at the corner waiting to cross.
I grew up in an older suburb that made judicious use of yield signs (give right-away to pedestrians AND vehicles). I remember being told as a kid to always give the right-of-way to cars and only cross when the intersection was clear - Smart advice from my parents, because cars had no issue zipping thru the intersection without slowing down while I stood at the corner waiting to cross.