There was a court case where they said that if they copied the books it's not fair use because they didn't own it but if they bought physical copies and then destroyed them then somehow it was fair use because it fell into the niche of personal backups. I forget the details but basically they buy one time prints and destroy them immediately.

I had no idea about that, or how fucking bad this actually is:

https://en.wikipedia.org/wiki/Project_Panama

So I stand corrected: at least some don't do it because it's cheaper (than to buy a license, or simply forego some things), but because they're fucking evil, or so stupid that it effectively is the same as being extremely evil.