Offer customers "You can pay $$19\mathrm{.}99$ to get the item TODAY!", knowing they will reject this rather extreme option and choose a more moderate option

Pre$-$select free no$-$rush shipping option for all AmazonPrime members, necessitating an active switch to a different shipping option At checkout, remind customers that, "Good AmazonPrime customers like you help us and the planet by choosing free no$-$rush shipping!"

Raise the amount of the digital reward to $$10,$ increasing the customer's financial incentive to choose free no$-$rush shipping

Change nothing$--$the set$-$up as shown in the picture $($where customers are simply reminded at the top that they would receive $$1$ in digital rewards if they choose no$-$rush shipping$)$ is already optimal