AT&T was prohibited from entering the OS/software business by the consent decree of... 1956, I think? They legally could not make a business out of selling Unix. So they distributed the tapes for more or less the cost of the tapes, IIRC.

Yes, that is how UNIX and C won the OS wars.

As soon as they were allowed to profit from UNIX, the Lion's book got forbidden, and the BSD lawsuit took place.