Video games are particularly egregious because even if an old game is currently sold under the same name, it often is not the same game:
* it’s running via emulation or has been recompiled for a different architecture with noticeable changes from the original (control latency, graphical differences, fixed/new bugs)
* content has been added or removed (often due to licensing)
* an EULA has been added or modified
* it’s not playable on the hardware where it was originally released
This is unlike books and music, which rarely change, or movies where it happens but is certainly not common.
Video games are different, though. The Genesis version of Sonic 3 has a different soundtrack than all others and hasn’t been available since 1997. Symphony of the Night had the most similar rerelease in 2006 on XBLA, but everything since has been a version with many big fixes and additions based on the PSP version. Final Fantasy VI has had many “enhanced” versions, but surprisingly the original ROM was available until the Wii U eShop shut down last year. Also aurprisingly, new old stock of the PS1 version could be bought from Square Enix up until a few years ago.
There are countless other remasters or ports that replace the original which is then never sold again.