Everything is illegal, or soon will be.
… we spend large sums of money on salaries for local legislators, state Poobahs and the Great Elite in DC to get wonderful results. We know you sleep more soundly knowing your street is protected from persons who might violate this ordinance.
A member of the local constabulary most likely has nothing better to do than patrol the area around such signs to deter and or capture miscreants violating said statute.
On the state and federal level the hue and cry over school shootings has our stalwart Overlords struggling to find the Grail to end forever the horrors of America’s misguided youth.
They came up with this, the Golden Nail to seal shut the lid to the past.