WHY...are there so FEW tv's..from the late '60's -to mid-80's STILL AROUND?

[rca2000]

It seems that most of the time we find an old tv-- we have a BETTER chance--of it being from the late '40's to early '60's..than from the mid-60's to the mid '80's. I do NOT understand WHY this is the case. 60+ YO tv sets should be MUCH harder to find than one 35 or so YO...but that is often NOT the case. Take Admiral for example. Most ANY ad for one...will be for an admiral from about 1948-55 or so, MAYBE early 1960's.. Almost NEVER for one newer--even though they SHOULD be around. Example--Admiral 1973 M20 7 tube hybrid..I have only seen ONE..35 years ago...not ONE since then...but have a FEW late 1940's admiral BW sets..

Or philco sets. Not real hard to find those early 1950's philc split chassis sets, or late 1940's philco sets (EXCEPT.for a few..like the 48-700 or 50-701/702. HARD to find..) are easy to find...but NEWER ones--like maybe late 60's philco BW sets or early '70's SS philco sets..? RARE !!

WHY is this? WHY.. was it EASIER for me to find a CTC 5 set--TWO of them in fact--than ANY of the late '70's RCA direct address sets? I STILL can't get hold of ONE of those..


Or Sylvanias. Sylvania sets are rare altogether...but I CANNOT find a 1971-72 EO-1 or EO- 2 set--that SS one with the early varactor tuner..to SAVE MY LIFE..but that 1948 syl set with the RF HV supp;y--I had one and have sen another one.

WHY IS THIS?????