It's a matter of approaching scenery design. We design our airports with usability first, with obviously a great attention to GSX so, especially in the later ones, like KIAH, everything we placed was based thinking how it would affect ground services. This sometimes results in users complaining the scenery doesn't look "busy" like others, although they usually are better in performance.
Lots of developers, instead, stuff the airport with static detail you can't remove, so they look busy and detailed on screenshot, but then you are left with a less usable product, because of fps impact, high number of objects, and worse ground services, all things that, to me, SHOULD matter more than make nice screenshot.