Apologies if this has been asked before, but why are so many HST carriages still being sent for scrap?
In recent years GWR, Scotrail and Cross-Country have all reintroduced HSTs (after refurbishment) so the HST power cars and carriages currently off-lease should be kept in store as they may be a chance that they can be put back into service at some point.
The comfort levels and general ambience on an HST is far better than on Voyagers, IEPs, IETs, etc.
Scotrail and GWR are effectively half-length sets, so a lot of surplus Mk3s there. XC haven't re-introduced them - it's the same five sets they have had for a long time, with upgrades done now and a couple of spare power cars acquired (they had none before this).
The EMR and ex-LNER fleets have no long term use, so a number of the Mk3 sets have been scrapped too.
The ROSCOs wouldn't be scrapping them if they thought there was a realistic chance of finding companies to lease them, so clearly they have decided that it's the end of the line - storing vehicles costs them money, and the longer they are stored the more they would cost to reactivate.
No power cars have been scrapped yet (other than the three which were written off years ago in accidents), which is perhaps somewhat surprising although one has been stripped for parts and at least four more are having the same treatment and most of those will most likely be scrapped in due course.