I've always thought that libraries needed tiers for their patrons. If a patron decided that they wanted access to books, movies, and other library materials and resources sooner than others they could pay a regular fee and they would get the first chance to reserve new materials. My guess for the reasons that this hasn't happened are similar to those reasons that college football students don't get paid; it's a publicly supported service and people aren't comfortable allowing some market forces to enter those areas.
It turns out my library already does offer certain users books ahead of others but it's not money you need, it's time. This fall I checked out 1,000 Dance with Dragons and I currently have the 800 page 11/22/63 both of which had two-week borrowing periods. Two weeks! With both Dragons and 11/22/63 I've read nothing else, watched very little television, listened to no podcasts, and neglected any chores related to a bathroom. I was slighly perturbed, wondering why newly released books this long didn't have an extended borrowing period but not anymore.
With two-week borrowing limits the library is allowing those people who really want to read the book to have first access to it. Those are very likely the same people who would have paid a regular fee for the same availability.
I probably won't finish 11/22/63 before I need to return it and whether I come back to it is unlikely, especially if I leave in one of the - frequent - dry spots, but I can appreciate what the library is doing whether it's intentional or not.