Great post and conclusion from an every day observation. I think the opposite lesson can also be made: Whenever you see people experiencing some kind of frustration, think about how you could develop a product that would make people in that exact situation just a little less frustrated.
This is a great lesson for developing a sales strategy. People are more willing to do things if you bring it to them. Even more so, offering something that gives an automatic solution to a current problem will most likely create a sale. Simple idea, but great to apply to every sale.