illegal daycare

A couple moved in across the street from me several years ago and when I first met them they explained that they had been run out of Asheboro because of the excess traffic caused by their
daycare center.  We live on a street with four houses so there really should not be much traffic but the traffic is so bad that sometimes I do not know who is in the neighborhood legitimately and who is up to no good.  It is not just the daycare center but one neighbor who runs a used care lot and parts department for his loud Mustang business and also from the other resident who raises livestock and does who knows what.
   I believe the illegal daycare has finally been closed but I just don't understand why the other neighbors are allowed to operate businesses that require their customers to come to their house.  What is the purpose of having zoning laws if the city can't or won't enforce them.