TheSagaContinues

I don't believe it is needed and that the reason you see it in the media is just to let the VIEWER know that something is happening and who is responsible.  At least that'll be true for most things but there are a few which likely are going to be more obvious.

When it comes to detecting the use of the Force I figure this is one of those "disturbances in the Force" that a Force Sensitive character could pick up on.  For someone without that skill detecting Force User should be a good bit more difficult assuming they even have some idea what may be going on.  I mean if I have a Sith Assassin sitting in a crowded bar I think it probably could utilized Force Grip to attempt to kill someone without automatically attracting attention to herself; another Force User in the bar probably should be able to pick up on that and even home in relatively easily but for anyone else it'd likely be a pretty difficult Perception check to realize "something is off about that person in this situation" yet it still wouldn't say what's going on.