No Backpacks or Large Bags

The sign greeting us on the door of the Gettysburg National Military Park Visitors Center read, "No Backpacks or Large Bags Allowed". Phew!, I left my backpack in the car. A woman at the doorway with several children and a friend was debating whether to enter. She had a large diaper bag. Her friend said she shouldn't enter but the woman said that was silly, it was more of a purse than a bag. Guilt-ridden they entered without consequence. The Electric Map presentation was held up at the last minute. We all waited, and waited. Then here comes a bus load of teenagers from what we think was Brazil. Their bus got there late. Here's the catch. Most were carrying large backpacks. So who exactly was the sign on the front doors for? Do they think the terrorists will stop at the sign and turn back? It only stops people that follow the rules and what good does that do, are those the ones you want not to enter? I wonder if the people in charge actually think those signs will deter any terror-inclined people. Without enforcement it is worse than no security at all, it becomes a joke.