A household has its own need for rest, preparation, and privacy. Where reasonably possible, a traveler returning after a long absence should give notice. This is about mutual consideration, not suspicion or intrusive supervision.
Example 1: Someone returning after weeks away can notify the household of an approximate arrival time.
Example 2: An emergency may require immediate return; the appropriate course depends on the circumstances.
The caution in فَلَا يَطْرُقْ concerns the combined circumstances of extended absence and an unexpected nighttime arrival.