> Is it too conceited to argue that each application is more unique than each housing structure?

I would say the exact opposite, actually. Two random software applications designed for the same purpose are likely much more similar to each other than two random buildings that were built for the same purpose.

This is because, for practical reasons, the software applications are likely just going to be slight variations of the same base. Unless your application is extremely intricate, most of the complexity (and most of the code that's executing) is actually in the kernel and the libraries. You're mostly just reusing those shared components and arranging them in a slightly different way.