Which is correct

I recently read a debate on one of the Facebook groups as to which way round should the front indicators be!

Are the orange indicators on the outside or the side light? The correct way is as shown in the photo but you see many cars with it the other way round.

The more I think of it the other way round gives better indicator visibility from the sides and the profile of the light aligns the flatter face pointing forwards.

Apparently the correct way was based on lighting regulations at the time.