It's a couple of things...
Simplistic EBay classifications...you want to distinguish yourself from the other kit cars, ranging from Gazelles to gawd knows what, you use the Shelby listing. Maybe someday EBay will break it down or have a seperate listing for the vast majority of kit cars, ie., "Cobra-based".
Alot of it has to do with American slang trands. We tend to shorthand products by refering to them by their original manufacturer: Xerox, Coke, Levis...
Some of it has to do with panache (or panoche for our latin friends)...borrowing the name of the provider of services or the product that carries some esteem: Rolex, Mont Blanc, Trojans...
In any event...
