I believe the game mechanics simply consider anything picked up at station A and dropped at station B that results in +Cr to be trade progress. Since passenger sightseeing missions from station A return to station A to complete, there is no +Cr from any other station so no "trade" progress, however since scanning a beacon is required, the +Cr difference is considered to be exploration.
You could get Elite Explorer and Elite Trader without ever going to any other systems besides Ceos and Sothis. Imagine Lewis and Clark only went to the local creek 3500 times, or Sir Edmund Hillary didn't actually climb Everest, but he climbed a total of the same distance by walking from his outhouse to his back door every day.
You could get Elite Explorer and Elite Trader without ever going to any other systems besides Ceos and Sothis. Imagine Lewis and Clark only went to the local creek 3500 times, or Sir Edmund Hillary didn't actually climb Everest, but he climbed a total of the same distance by walking from his outhouse to his back door every day.