It’s not your customer’s job to know what they don’t. That’s your job. It’s your job to lead them and help them see possibilities which are hidden from their worldview. It’s part of the value of working with you.
If it was any different, then the customer would not need you. They could lead themselves and get to what they want.
This is why educating and building trust with customers before the sale is so important today. It helps them to get comfortable with your domain of familiarity. Of course, that means a lot of initiative from your side both before and during the sale. But here is where your opportunity lies compared to your competition. You can own the entire experience and fill in the knowledge gaps for someone desperately seeking a solution.
So, in your own business, how can you help the customer know what they don’t? What would it take?