I don't think it is callous at all. But if you do not care what the customer thinks the price "should" be, why should you feel that he ought to think the price you want is what it "should" be?
The way it works is if the price you are offering exceeds what a customer is willing to pay, he will pass on it. he may come back and ask you to rethink it some, or take something out to make it affordable, or the whole project may just go away. or the project might well go to someone who bid more in line with what he wants to pay, or can afford to pay.
I would not be so quick to assume that just because another business bid less than you did that it was below their cost. There are some people who have whittled out every nickle from their cost structure and are very lean. They would not have managed to survive this long into a sucky business climate if they were losing money on these jobs every time. Somehow they are making enough money to stay in business.
I am one of those lean guys. Its a critical to understand true worth of money and what value is. It would be understandable to think just blurting out "its below cost,' is uneducated guess. I'm stating the obvious but, business is all about relationships. Its important to have relationships that get you the kind of information that allow that kind of statement to be valid. The customer should see the value you can offer value, and understand what a profit is. Allowing yourself to be beat down, bid shopped and/or finagled into no profit is foolish.
Every business transaction made must have value, or its not business. You can successfully argue that losing a few to win the bid ones is valuable. This is not the case most of the time in electrical work. I spend a lot of time micromanaging expenses/costs (not people), and developing relationships. Customers set the market price. They have found a way to pay less, taking advantage of ignorance. That ignorance of business cuts us all, even if just a small amount. Seems you have found a way to take advantage of that ignorance as well being a lean guy. I do not mean that in a derogatory way. Do you feel you are the exception not the rule?