Yeah, that is business for you. As much I love the free market, you cannot expect free market restaurants to set out to better our health. (I was really joking earlier when I said that restaurants charge you more for adding meats to salad to better your health)
I wonder why. I wonder they price the menu based on people’s pocket. Usually speaking, health conscious people are also more willing to pay more. Although the other argument is that steaming is slower than stir fried, so they may charge based on time.