What happens in reality is someone writes the spec as "40% of the unit price" or something, and that gets taken from some DB table at Amazon that has "unit pric

What happens in reality is someone writes the spec as "40% of the unit price" or something, and that gets taken from some DB table at Amazon that has "unit price", but the meaning is different from what the spec refers to as "unit price". Meanwhile both sides of the interaction (Amazon and the publishers) are using words they recognize, but with different meanings behind them! And both sides are so used to seeing the words that _of course_ it's the right thing (until it's not!). Of course the reality is probably more subtle than this, but spec documents don't save you from domain knowledge (or lack thereof) 100% of the time. Definitely helpful as a reference document, of course! And it eliminates a large class of discussions.