I was able to purchase a LTO-7 library full of tapes a few years ago for basically nothing, and still haven't gotten around to using it. There seems to be very little in terms of free, automated software for managing the system and performing tasks such as backups. tar doesn't exactly cut it for hands-off usage.
The best I've found is using Veeam Backup & Replication, but it's Windows only and not great still.
That's fair. I used to use Ark, which was mostly a proprietary front-end for bacula, and that exposed me to the kind of futility of a "user-friendly" tape interface. Every tape operation from picking to winding to r/w takes so much time, and has so many subtle ways that it can fail, that it defies attempts at friendly user interfaces.
Bacula is great software, but yes, fiddly to set up and SCSI tape drives / changers aren't really straightforward either. It will serve you well once all is set up though.
I worked for a company using Bacula quite successfully for many years with a 24 tape system. It was much better than the proprietary software the system came with.
For backups I'm using BareOS, which is a fork of Bacula. For archival... We wrote our own software, which is mostly free (AGPL3). I should give our github some love though :)
https://github.com/Intellique
The best I've found is using Veeam Backup & Replication, but it's Windows only and not great still.