Well, either Lucasfilm was spouting disinformation back then, or it's doing so now because nobody really remembers what happened anymore. Parts of the Dagobah set were supposed to be stored for Jedi as well.

You'd think there would have been multiple takes of the exterior of Yoda's house leftover from Empire though.

I do know small pieces of the Falcon were contest prizes given away by the original SW fan club in the 80's.

As to British Labor laws, if you listen the commentaries on the Bond films, they reused M's office set all the way into the Roger Moore era until it was too worn out or rotted to be rebuilt again. The double red door 007 entered through was saved though.

If you've seen the PSA restored and included on Puggo Grande, that set is clearly made from walls of the Death Star control room. The ad was shot long after Star Wars wrapped filming.