They do not have a contract with the publishers. Their normal CDL policy (one digital copy loaned out per physical book in the archive) is legal under fair use. The publishers also have a motion for summary judgement, which would prevent them from doing this.

The publishers would rather rent them a digital copy for a lot of money, that is either time-limited or has a cap on the total number of times it can be checked out before the Archive would have to pay again.