alt Hacker NewsYou should be talking about the compilation process, because that's the thing that puts the cost of non-novel software at near zero, and you can't recompile a bridge for free.
Estimating the duration of each step of a process only works when you know what the steps are.
Effectively free distribution is what makes the cost of non-novel software so low. Compilation isn't even needed for executables that can be used as is.
That said, implementation is one part of developing software. Design and test are also necessary and can take a non trivial amount of time.
And yes, you need to know what the steps are to build something. If you don't, you don't know what you're doing, which is a bad thing.