"Honesty" is a logistical headache when it comes to recorded performances. Imagine, before digital distribution, tracking every movie ticket, every rental, every purchase (don't forget discounts like matinée tickets, coupons, clearance, etc), every clip used where royalties are due, etc ... and paying royalties to every face in your movie, at various rates depending on screen time or 'voice' time...

As the talent, it's just easier to demand a large payment up front and just forget about the royalties. As the studio, it's easier just to pay that amount up front. Then, magic voodoo accounting and poof any statutory royalties are eliminated.

I suppose in this case, the "honest" studio is negotiating that large up-front payment to its talent rather than trying to sell the talent on the eternal royalties that never come.