I understand the joke, I think. But what do the devil and Jesus have to do with it? If either one of them is evil it’s what Jesus is saying, so that can’t be it. What am I missing here?
Because it’s an extra expense, not just to install but to maintain. They put them on the exterior door because it lets people in faster and easier (more customers) and is easier to haul out your purchases when you leave so you are encouraged to buy things without thinking as much about logistics. Bathroom doors being automated vs manual is almost never going to affect sales.
Your example introduces the axis of time which is not in consideration when discussing infinity. You’re literally removing infinity from the equation by doing that because “at any given point” by definition is not infinity. Let’s say that point is 1 million bills down the line. Now you’re comparing 1,000,000 x 100 vs 1,000,000 x 1, nothing to do with infinity