They only make a certain about of any given album. Then they stop making it. It's out of print. They become rare. Record companies often don't want to invest in it again (sometimes they do), and there's lots different vinyl companies and/or record stores that will do a pressing of it and re-release the vinyl.

And not only that but you've seen re-releases your whole life "20 year anniversary edition," "Deluxe edition" those are re-releases.