So because we take the car to the track and attempt to reach a goal it becomes a track car? By your logic there are no street cars if they go to the track. Was my 1999 honda civic bone stock a track car?
So you would choose to ignore the risks of having a cage in a street car that spends 99% of the time on the street for the 1% of the time it goes to the track. Not to mention how dangerous it would then become for the passenger also.