Sadly most programmers are introverted and not well-articulated (which is much worse than being introverted). So when it comes to them you are quite right.

However, as a counterpoint to yours, even those of us who can communicate quite clearly get met with very ugly accusations of ripping customers off. People simply come to you with a preconceived notion about how much something must cost (in terms of money, effort and time) and they are absolutely not willing to change that notion -- even if they are on the side of the pure imagination and you are on the side of the facts.

It's basic psychology that many of us had to learn even if we never wanted to.