Tape also has other overhead... like you need a reader and if you’re operating at the scale where the cost of the tape is a deciding factor, then you probably also would like to have an auto loader, rack mounted gear, etc. Not to mention the different software needed and keeping track of what is on tape (which tape?), vs disk is a lot to manage.

For many, just keeping multiple HDDs around, even if they are slightly more expensive is the simpler option.

What's the actual cost of ownership? I have never found a drive + tapes system that made financial sense, but I'm willing to be shown the error of my GoogleFu ways :-)