Operation security at Yavin IV should be maintained at all times based on the importance of individuals visiting and taking part in the rebellion. Movements on and off the planet would be of utmost importance to monitor as any Imperial spy making off with a spaceship would be devastating to their operation. Here a former Imperial pilot operating an Imperial vessel taking off from the rebel base despite failing call sign check, authorization check, and clearance check.
Even the Rebel Sentry fails to take action when it launches. Standard procedure appears to be that the sentry scans all inbound and outbound ships, the Jedha outbound ship was monitored by the sentry on duty, but the Rogue One ship was not expected to take off.
Why is Rogue One allowed out of the atmosphere and particularly out of the solar system?