capturing all your money is better for the producer than just capturing the producer surplus (and the marginal utility of the consumer surplus to you is sufficiently low that adding it on doesn’t bring the surpluses to a higher number).
By assumption, the consumer surplus to me is $30. Which is high enough to bring the surpluses to a higher number. I’m not denying that there are slightly different constructions of the problem where donation is the trivially more moral action. That’s not the point, though. The point is that, in this particular scenario (where, by preference fulfillment/K-H efficiency, buying>donating>keeping my money) my moral intuition says to donate or keep the money. You’re making further assumptions (U(consumer surplus) is approximately 0) which make the problem easier, but less interesting.
By assumption, the consumer surplus to me is $30. Which is high enough to bring the surpluses to a higher number. I’m not denying that there are slightly different constructions of the problem where donation is the trivially more moral action. That’s not the point, though. The point is that, in this particular scenario (where, by preference fulfillment/K-H efficiency, buying>donating>keeping my money) my moral intuition says to donate or keep the money. You’re making further assumptions (U(consumer surplus) is approximately 0) which make the problem easier, but less interesting.