alt Hacker NewsYou assume what they say is the same as what they are thinking
The converse is also true. People saying something assume that people listening are understanding and thinking about the same thing. This is why it's important to write things down in details and as-unambiguous-as-you-can forms.
If you're in a meeting and someone puts up a slide deck with a 6 word bullet point that 'explains' what they want, that is a signal that literally no one understands the goal. If they put in a meeting without writing a one page doc about it, they don't understand it well enough to explain it.
And if your progression hangs off delivering that thing, you should by demanding that you get a clearer picture.
Replies
What I say: This is not ready for production.
What management hears: We can sell this to the customer for acceptance testing.
You also need to force them to justify their requirements, since asking for something way beyond what you actually need is an easy way to hide the fact that they don't understand what they actually need.
In my experience, people like that asking for 10x the actual requirement is fairly usual. But, every once in a while you hear someone say "we should buy the best, so we don't have to worry about it in the future" (when I heard it, that was a 500x cost difference).