I've always wondered how one gets so many cars? Who would spend the money to park it and let it rot. The only thing I can come up with is that it was a thriving junkyard in the 50's and the 60's before it closed and was forgotten about?
Many times, you can find junkyards that were never thriving, full of very old cars. Some guys bought old cars, filled up what looked like a junkyard, and never sold anything off them, because they just didn't want to. Some guys just are eccentric that way.
What usually happens is the old guy dies, and the crusher is in there a week later, and they crush GTO's, 57 Chevrolets, whatever is in there, as fast as they can go.