Do law firms outsource copying to a vendor but receive a financial interest from them?

A short note in an article troubled me: “firms house what is represented as an independent copying vendor … without disclosing to the client any financial interest that the firm may have in the vendor.” The article is in Lit. Mgt. Rep., Oct. 2009 at 4, by Rick Hauser, an invoice review attorney for an e-billing vendor.

I have speculated on law firms getting rebates from airlines and whether the clients who paid for the ticket benefit from the rebate (See my post of Feb. 14, 2007: back-end rebates from airlines but not passing them through perhaps.). For them to get rebates from copying services or some other kind of financial kickback is fine so long as clients who paid the full amount for copying share fairly in the recompense.