I think your comparison is out of date [1], AWS S3 infrequent access has $0.0125 per GB now not $0.022+ that you have listed. Of course yours is still much better with $0.005 per GB.
Also, it does not look like you have any kind of consumer offering for it, as I have to contact sales to get anything at all. So there's really no point for Arq to even try adding support. I like your prices though.
We don't write out the infrequent access pricing as it's not what we're competing with, also why we don't price out Nearline or Glacier, it's not at 1:1 for what we're trying to offer. The consumer offering is available from the docs: https://www.backblaze.com/b2/docs/. You can use the web interface if you want, or tie in with CLIs/APIs. The sales channel is primarily for people that want to integrate it in to the apps that they are building. Hope that clears some things up!
Also, it does not look like you have any kind of consumer offering for it, as I have to contact sales to get anything at all. So there's really no point for Arq to even try adding support. I like your prices though.
[1] https://www.backblaze.com/b2/cloud-storage-providers.html