Honestly, I'm not sure.
On one hand, I think this is pretty cheap of Kuchar and would like to think that he would do better. On the other hand, what does he owe the guy?
What they agreed upon could certainly be the answer
An industry accepted number could also work if there is one (I tip 20% because that seems like the correct thing to do...)
I cringe a bit that the caddie says he deserves more. Deserves is weak, either you agreed it and earned it or you didn't.
I can hear practically my kids saying what they deserve (I deserved an A in that class... I worked hard, I deserve a vacation)
In any case, I would have taken the $15K additional..