Tell me if this sounds familiar:
I usually know what I want. When I’m ordering fast food, I like quick service. I call the place up, say what I want in quick succession, and simply ask how much I owe. That gets paid and consumed, usually while thinking about something else, and it’s all over.
Now imagine if I tried doing that when I need the services of a surgeon. “Hello, I think I have a brain tumor. How much would you charge me for cutting the skin on my head, and removing the offending bits, preferably on a Tuesday morning? Why not? Oh, right, I completely forgot about my skull. Could happen to anybody.”
Commoditized services are quite unlike expertise-based professional services. In Starbucks, the barista correcting the customer’s brief would be considered rude and most unwelcome. In an architect’s office, correcting the client’s brief is at least 40% of the expected value.
The client knows what’s their problem, and how much they can afford to fix it. Everything else, very much including the actual scope of the work, is a part of your job. You are a professional, you know what needs to be done to get where the client wants to go better than they do, so what is the sense in leaving them to figure out the scope? In my mind, that’s how everybody loses.
Correct your client’s brief, and charge for it. It’s as much a part of your job as is working on the problem itself.