Or by people who realize that it's not worth the effort to try to get more than face value for them, and that their value is likely to increase much more slowly than the rate of inflation. I've received a BU 1986 Statue of Liberty commemorative half in change from a dealer at a show. Later NIFC Kennedys are likely to be even less desirable.
I've pulled at least three proofs (two quarters and one half) from circulation during the past year... NIFC halves are really not much different.
Am I correct in saying that 2002 and later 50 cent pieces were/are available *only* directly (new) from the U. S. Mint? Even though they are not proofs?
People buy them in bulk and save the nice ones for resale or grading. The rest are deposited at face value. NIFC halves are 1987 and 2002 to date.
This is correct. You can find them though. People break up those mint sets more often than one might think. People seek to fill holes in books, and sometimes get ride of the rest.