This is because commercial optical disks and recordable optical disks are actually completely different storage mediums.
Commercial optical disks, as in the disks that you got when you bought games and movies and the like, are physically stamped. The data is recorded as physical pits that are stamped onto the disk from a master copy. That disk isn't degrading unless it suffers severe external physical damage.
By contrast, recordable optical disks write their data using inks and dyes that are burned by a recording drive's laser. These inks and dyes can and will degrade over time, eventually leading to data loss.
True in general but there are, as always, exceptions. Some more expensive recordable discs use really stable dyes and remain readable for a very long time. On the other hand, some commercially pressed discs also suffer from bit rot.
I have some mid-90s CD-based games that have become partially unreadable due to that. Some CD pressing facilities are known to have produced lots of discs at certain times that are now faulty.
Commercial optical disks, as in the disks that you got when you bought games and movies and the like, are physically stamped. The data is recorded as physical pits that are stamped onto the disk from a master copy. That disk isn't degrading unless it suffers severe external physical damage.
By contrast, recordable optical disks write their data using inks and dyes that are burned by a recording drive's laser. These inks and dyes can and will degrade over time, eventually leading to data loss.