You need a limiting principle or there is no limit to the "better funding" you're asking for until you have a Library of Congress in every small town in America, to no positive effect.
What's the limiting principle you propose? It has to be something real libraries and library funding sources can take action on, because they have to take real-world actions on them. So this is not a time for aspirational speeches or vague exhortations to "do more", which is the exact opposite of a limiting principle anyhow. What is "enough"?
The limiting principle should be that for a given ILL region/system, there is at least one copy of each book/edition which entered that system which can be loaned out.
As I noted, it's a pain for me to have to drive down to DC to get access to a book which _used_ to be in the local library system, but isn't anymore, or to purchase my own copy (which wasn't previously necessary).
This is a REALLY bold assumption you’re making here, and frankly until we’ve tried it I don’t think you can argue that it has no positive effect to put tons of books in every small town everywhere.
Sure, there are always solutions, and many of them usually involve more money. But that money usually doesn't just magically appear, even with plenty of Carnegie-types these days looking to whitewash their reputations through philanthropy. The money often is the problem that needs to be solved, and there's just no source for those funds.
I used to work in a bookstore, and I've been working in libraries almost my entire career. Most books have no value. I've probably thrown out a million books in my life; most of them have been diet books, cook books, and political biographies.
My current library is around 2000 square feet and I acquire around 1000 books a year, so I have to toss around 1000 books a year, because they're made of matter and take up space.
Someone needs to take up Carnegie's mantle and finish the job which he began.