Probably detail. That $95 model was probably produced by scanning an actual vehicls. The others are produced by box modeling off a 3-view drawing.
I dropped $25 on a model years ago.
![](https://ecomodder.com/forum/member-freebeard-albums-photoshops-picture6253-four-tails.jpg)
The software (maybe the hardware) made it impractical to modify the original so I just hung kludges on it. I should take these into Blender, it does Booleans.