I’ve been told that box leather is relatively scarce bc much of what is produced doesn’t meet quality control, and epsom is the result (of failed box). At Duret, a leather artisan in Paris, I’ve seen his collection of hides, among which is 50 year old Box leather, and it’s amazing.
In addition, the boutiques do get complaints from clients who unrealistically expect their box bags to remain pristine. New clients may not understand that the patina arises from the inevitable network of scratches that are repeatedly polished and burnished into the box leather glow. Hermes spa is always pleased to see well cared for vintage box.
To tie this back into prespend, these characteristics of box is why box leather doesn’t get offered simply to those that spend more. It’s really for those who love it. And, some of us who do love it really feel that vintage* box is the best.
*I prefer box Kelly bags that are early 2000s, so have the beginnings of patina but also the double rings for the strap. So technically not vintage

Years ago, Claude at Madison replaced a 1985 BBK28 handle and provided double rings, but I’ve been told differing reports as to whether Spa will do that today. Have not had a handle replacement recently, so haven’t tested this.