Other than U of Toronto, Catholic universities have been very slow to scan their formidable collections of library books now in the public domain. Very slow. Slooooooow. And of course, a lot of seminaries, orders, and similar institutions threw out books rather recklessly in the Sixties, Seventies, and Eighties, so some of them don’t have the old books around at all. There are a lot of reprint houses, of course, and a lot of universities with books you can visit, but first you have to know what you’re looking for and what is authoritative and useful. Nobody can reprint everything. Moreover, some of those big ol’ tomes aren’t easy to scan.
The odd result is that a lot of collections of formerly-famous, now-obscure, theological books on CD are still kicking around in the Catholic world, well after most people have been able to trust to the Internet Archive (or even to “borrowing” e-versions of books from its new Open Library).
The Ite ad Thomam Out-of-Print Library is a particularly big one.