How can there be BeatlesMaster Tapes outside of Record Company Vaults? outside of - Museum of Master Tape Reels

Existence of Beatles Master Tape Reels outside of record company vaults – how did it happen?
Believe it or not, there are a large number of actual master tape reels circulating among collectors and available for purchase (the master itself or a copy). A few were stolen from the vaults by errant employees, but in fact most Master Tapes were literally thrown out when studios moved wholesale to digital recording and purged their analog media. A number of those tapes from studio vaults were recovered from the dumpster by enterprising individuals, often employees themselves. This has happened at a number of record studios and recording studios including EMI Abbey Road-produced copies of Beatles Master Tapes made for Discos Capitol de Mexico, Gamma SA, Mexico, Jugoton (Yugoslavia, now Croatia), Odeon Spain, Sterling Sound, US, EMI Svenska (Sweden), Dideca Guatemala, and both Sono Cairo (seventies) and Sout El Hob (eighties) from Egypt, as well as others.
On the site you’ll see examples of these tapes. There is also a discussion about how to identify them and discern real master tapes from fakes - the clues for determining authenticity. We’ll discuss the recording and mastering processes to determine what constitutes a master, safety copy, 1st, 2nd generation, etc. We've included photos to help identify Master Tapes along the way.