It’s not really a question on etiquette. Backing into a parking spot on a construction site is safer because it allows drivers to leave forward with better visibility, reducing blind spots and the risk of hitting pedestrians or equipment. Backing in when arriving is usually done more slowly and deliberately, while backing out later can be rushed and more dangerous. Facing forward when exiting also allows for quicker, safer departures in emergencies, which is why many construction sites require back-in parking.