In a nutshell: There are justifiable concerns about the longevity of digitally stored data, especially in Japan, where certain tax-related information must be preserved for 100 years. It's led to manufacturer Pioneer developing Blu-ray discs that are guaranteed to store data for at least a century.
As reported by PC Watch (via Tom's Hardware), Japan's Electronic Books Preservation Act requires certain tax data to be stored electronically for 100 years. That's a problem for long-term digital storage formats such as NAND flash, hard drives, tape, and optical discs, which wouldn't last a century.
Pioneer has offered an answer to this problem in the form of the BDR-WX01DM, a USB 3.0 (Type-A) Blu-ray optical drive, and 25GB BD-R discs called IPS-BD11J03P. Both carry the 'DM for Archive' label and meet the Japanese government's JIS X6257 quality standard for guaranteed longevity.
The drive uses reliable motors, durable mechanical systems, and a dust shield structure. It's also compatible with glassy carbon-based M-disc media that's designed to last 1,000 years. That all goes some way toward explaining the $400 (without tax) price.
The discs are also more expensive than your standard Blu-rays, priced at around $16 for a pack of three. However, users will have to pay extra costs to store the discs in special environments with temperature and humidity controls. It's also recommended that the discs be kept in buildings with fire, earthquake, and flood protection if you really want to help ensure they survive for at least a century. Given that these products are designed for enterprise and government customers, the high costs and maintenance requirements are unlikely to be big issues.
Back in 2019, Warner Bros. and Microsoft collaborated on a proof of concept test for Project Silica, a Microsoft Research project that used laser optics and AI to store data in quartz glass. It resulted in the entire Superman (1978) movie being stored on a piece of 7.5 cm x 7.5 cm x 2 mm glass that should last for thousands of years.