Refused - return to sender. What happened??

Was expecting a parcel today. I heard the postman put something through the letterbox so I assumed the parcel fit through. No knock or doorbell. Went to the door shortly after and it was just two letters.

Went to the tracking and it was marked as delivered at 10:47am and then “refused - return to sender” at 10:50am. The picture proof of delivery was taken at someone else’s house - can tell from the paving stones.

Why did he not try and deliver? And if it’s a case of he realized he had it later in his route why mark it as refused?