>>>Little to do with scrummaging.
>
>Reference to scrum cap = the device that used to be worn to protect ears but increasingly is worn by backs as well.

Yes I know but (from Wikipedia so it must be true)

Since the early 1990s, other players have taken to wearing padded headgear. This is intended to protect from cuts and head injuries that can occur from incidental contact in tackles or at rucks. Whilst they may prevent some cuts and abrasions, such headgear has not been shown to reduce concussive injury.[