Providing signed/lined/dated copies of authors titles is largely a UK trend, and the authors are somewhat taxed to provide this service.  We arrange dozens of author signings each month and consider ourselves privileged to have relationships with the authors making this possible. Frankly, it is our "stock in trade."  Authors sign for us out of courtesy and it is our goal to deliver those signed copies to their fans.  Often these signings include hundreds of copies; to ask the authors to do anything more than sign them would be taking advantage of the courtesy. 

I have been at public signings where authors have been asked to line/date books and have seen some of them look at the number of people waiting and then decline to do so...or some sign anyway.  If asked, I would think that most authors would not encourage this practice.

I appreciate you desire for this enhancement but we feel if this becomes the “new standard”, some authors would limit or reduce their willingness to sign.