The scenery doesn't have anything to do with this, since it correctly uses proper airline codes for all the parkings. But if your AI don't have them, they will park randomly so, you might think you have "zero traffic", but they might just be in remote areas, because they are missing the airline code in their airplane.cfg files.
Zero traffic it's just not possible, unless you are using AI models originally made for FS9, which might be invisible.