Quite a long time ago, I think in the 1980s, an agent brought and won a suit regarding the deep discount clause. (kriswrites.com)
Why would this same 16 % increase not also apply to how much the author earns (unless there is some special discount clause in the traditional publishing contract that lowers their royalty — they wouldn't dare do that — would they)? (whatever.scalzi.com)
A standard deep discount clause looks something like this: «On copies of the Work sold by the Publisher at a discount of greater than 55 % from the publisher's retail price through channels outside of ordinary retail trade channels, the author will be paid a royalty of 15 % of the Publisher's net proceeds.» (goodereader.com)