There is nothing funny thereFunny - the AI aircraft don't have wheels. Do they use old FS9 ones?
It is an indication that the 3-D models were not yet continuously optimized at the time of the screenshot. Usually, data is optimized in almost all modern PC and console games. Be it terrain data, textures, or like in this case a 3-D model. The topic is about "Levels of Detail", the abbreviation LOD should be familiar to you, right? The abbreviation stands for Level of Detail; Depending on the distance to the object, details are shown or hidden. So it is no more than a reference to the LOD system that the developers of the MFS use to make optimizations