I agree that they are usually just dismissively labelled as "old"I've heard of the first one in literary terms but I thought it applied to the ones who died not the ones still alive now.
I don't hear people using these terms about themselves or their contemporaries, and I see a lot of people who are over 75. Don't hear these terms used in our media. 'Bed-blocker' 'pensioners' perhaps 'silver surfers'. Usually just 'elderly' or 'old'.