Responsible gun shop owners sink pylons deep into the ground in front of the storefront. It's impossible to drive a car into the storefront, for they hit the pylons first.
So the obvious question that arises is....why didn't 500 Guns have them?
Uh, they do have them. Ballards don't stop someone from PULLING bars AWAY from the building.
Edit: Churchmouse and Colt556 beat me.