Because the father -- one of the fathers of the Industrial Revolution, Adam Smith -- was convinced that human beings were by their very natures lazy, and wouldn't do anything unless you made it worth their while, and the way you made it worth their while was by incentivizing, by giving them rewards.
Laut einem der Urväter der Industriellen Revolution, Adam Smith, sind die Menschen von Natur aus faul und tun nichts, außer sie haben etwas davon. Damit sie also etwas davon haben, schuf man Anreize und Belohnungen.