This article got written because economists have a limited vocabulary for talking about design.
If you build a machine to solve a problem, and the machine doesn't act the way you want it to, that's a bug. Fixing bugs is easier than starting over would be. Bugs that make you wonder are called design flaws.
You don't get unintended consequences until your system works, and things change in your environment (or maybe with your users) because of the way it works. Unintended consequences are hard to fix because they only show up in systems that are already doing what you want.
If you build a machine to solve a problem, and the machine doesn't act the way you want it to, that's a bug. Fixing bugs is easier than starting over would be. Bugs that make you wonder are called design flaws.
You don't get unintended consequences until your system works, and things change in your environment (or maybe with your users) because of the way it works. Unintended consequences are hard to fix because they only show up in systems that are already doing what you want.