Do librarians not like working with shopping carts?

[adam hodgkin <adam.hodgkin@gmail.com>]

Is it the case that there is no effective and popular library service
that uses the shopping cart system (in the way that Dell, Apple, 
Amazon and many other web e-commerce sites do)?

I recognise that Document Delivery/ Pay-per-View services are normally
transparently priced and shopping carts are used. But are there any
other good examples of Shopping Carts in the world of library services
and resources?

If anyone has insight into this and wants to reply direct to me I will
summarise such replies for the list.

The question arises because I would have thought that the
disatisfaction with big bundle deals and the growing interest in OA
would encourage interest in transparent pricing of specific resources
(eg of author-is-paid content), but I see little evidence of this.

Adam Hodgkin