If a 20-30 year old in USA hadn't seen a Star Wars filmed I'd be really surprised.
If they had no clue as to who Barbra Walters is, I'd be not surprised in the least. That's be like expecting people of my generation to know who Will Shirer or Edward R Murrow are. I mean, I
know who they are but most of my contemporaries don't have a clue.
For those who asked, Barb was a big deal back in the day because she was the first woman in the US to chair a national TV news desk (as opposed to being just another pretty reporter). I use "pretty" as a relative term, here.