How's about Ven Chin-kung's Buddha Educational Foundation in Taiwan ( http://www.budaedu.org/en/introduce/
)? In the past 25 years, they have been printing a large numbers of Dhamma books in many languages for free distribution worldwide, with good quality printing. What is their financial model?
Donations, as you say.
Although there have been concerns/complaints on their violation of copyright, I sincerely admire their dedicated Dhamma work; and I for one, have been on the receiving end, benefitting many free good Dhamma books from them.
I have too.
There are also other smaller groups (susch as in Malaysia, Singapore) which print and distribute free copies of Dhamma books, and rely on generous donations from Buddhist readers.
And I have books from those organisations. However, all of the organisations you mention have limited print runs, so many of the books are unavailable, even if you were willing to pay for them.
Also, they have not produced anything that compares with the modern translations from PTS, BPS, Wisdom, etc. The books I have appear to be mostly material that was previously published elsewhere or is produced from electronic copy produced elsewhere (e.g. Ven Thanissaro's Wings for Awakening).
As others have said, taking existing copy and printing it is not particularly difficult or expensive. Producing the copy in the first place is the difficult bit. One might argue that Bhikkhu Bodhi could have done what Ven Thanissaro has done, and simply produce the electronic copy and rely on the donation-supported printers to distribute it. And perhaps someone will do that in the future. However, though I am grateful for books such as "Wings to Awakening", the production quality is not great, and for a major reference such as the Nikaya volumes, which I expect to use heavily for many years, I'd rather have something well printed and well bound.
Having said that, I'd really like a proper searchable PDF (not a scan) of those books to aid searching...