I agree. The tub and everything associated with the runing gear will be positioned to fine tolerances. The variable is the fitting of the mudguards. In the case of the trad the wooden frame is highly variable and the mudguards are cut trimed and fitted by eye (as are the bonnets). This is why we have the ridiculous situation that no body parts are interchangeable. Crash repairs that involve replacing parts must be a nightmare. The rear mudguards on my car are not even the same width. And the left and right front guards are fitted differently.
Can you imagine the same situation on any other car that costs as much as an Aero 8? It is bad enough that parts are not interchangeable on a trad, but on an Aero that has the major components jigged and manuafactured to tight tolerances the fact that mudguards are a variable and positioned by eye is impossible to comprehend.