They all share that quality of "its straightforward, anyone can just look up the details and make it"... a month later you're still chasing some detail as some

They all share that quality of "its straightforward, anyone can just look up the details and make it"... a month later you're still chasing some detail as some bureaucrat has added some new wrinkle. Now a rule change elsewhere has happened... it never ends. Plus each locality has its own history and the details all make sense for them but not necessarily for you and your codebase. Simple to implement but the complexity is getting it right for every case. None of it is easy.