Which is not a valid reason for failing to stop at a stop sign?

A valid reason for failing to stop at a stop sign must meet specific criteria related to safety and traffic regulations. The scenario where one is "in a hurry" does not justify failing to stop at a stop sign. Traffic laws are designed to promote safety for all road users, and being in a rush does not diminish the need to adhere to those laws.

Stop signs are placed at intersections to control traffic flow and indicate when vehicles must come to a full stop, regardless of the specific circumstances or the perceived urgency of the driver. Ignoring the stop sign because of a sense of urgency can lead to dangerous situations, including accidents, putting both the driver and other road users at risk.

In contrast, the other reasons provided, such as an obstructed sign or the fact that it might be late at night, can reflect situational factors that could potentially mitigate responsibility, albeit they still do not absolve a driver from the duty of ensuring safety. For example, if the sign is obstructed, the driver may not clearly see the requirement to stop, and if it's late at night, the driver might be justified in proceeding with caution if no other traffic is present. However, being in a hurry is simply an emotional factor that does not align with the principles