Write-only backup media and big archives

Not really a mechanical or procedural thing, but a little more philosophical as I think about data storage not just at home for classic computing, but at work: In the 90's the CD-R and soon after the DVD-R looked pretty ideal for making "write only" backups of what was then considered large amounts of data. While not archival in the centuries sense, it seemed a pretty safe bet that readers would be readily available for the next 10 or 20 years and I think this bet has turned out well. I was willing to spend an afternoon buring a dozen or two CD-R's because they felt "real". But today, a "large amount of data" is not a few gigabytes, but terabytes. Tape libraries with these sorts of capacities do exist but aren't available at the corner store and I have a nagging mistrust of tapes that causes me to refer to them as "write only memory". (I never really ever trusted anything denser than 1600BPI 9-track!). Burning 2000 CD-R's or even 500 DVD-R's doesn't seem like a reasonable or useful task to backup a terabyte hard drive (which today is a fraction the price of the 9 Gig drives of the mid-90's that was "big storage".) At the same time, the ubiquitous and available-at-the-corner-store terabyte-sized USB drives don't feel awfully reliable either. They are way more convenient and cheap though, and that's my prefered backup media today. I think I'm falling into the trap of confusing the price of storage with the value of the information recorded onto the storage. It's ironic that as disk space has become cheaper and cheaper, we regard the contents as less worthy of the effort of backup onto reliable media. OK, philosophy mode off. The NTSB is gonna be asking me for a few gigabytes of data next week and that seems easy compared to the terabytes at home.