Thanks so much for the response, Koen.
I think the idea that nudges don’t impose costs (material or otherwise) is one of the biggest misconceptions out there. Sunstein and Thaler pushed this idea, and I think it’s just wrong. If you look at any canonical nudge, you can find costs attached to overriding the choice.
Take the cafeteria example. At first blush it might appear as though there are no costs if you want the unhealthy food. But *not* acting on the impulse to grab the first items you see exacts by depleting cognitive reserves, etc.