Hand soap dispenser

Although the mechanism creates a lot of waste, they are convenient. But I cannot help wondering whether they are manufactured in such a way as to preventing people using the soap sparingly. The one I am using at home squirts out a lot even when I try not to. They have not designed the dispenser with economy in mind. Why can't they design it so that the user has much more control over the amount of soap that comes out? This way we won't have to use an excessive amount of soap to just wash our hands and we will not be contributing as much to the pollution of the rivers and the sea.