On the webpage that opens up for me when I click on the banner ad for the Audible sale, it says, "All titles are up to 70% off . . . so take some time to unwind and tune in."
So the promotional material(s) "promise" that there will be at least one title 70% off in the sale.
Some true tightwads (including yours truly) might bite if a price is 70% off, where he/she wouldn't if it was a measly 50% or 60% off.