In 1820 Henri maillardet has artificial the first robot in the world. It's like a caterpillar and has a duty to be a home decor. But currently it is developed to work like a human. however, there are a main difference between robot and human; expenses and performance.
Firstly, human has a lower performance than a robot. the performance of human is not sure, depending on their health and emotion. but the robot has followed the order certainly. The robot has a more performance than human and low error rate. Many companies choose robot because it has a high performance and a low error rate.
secondly, the robot has a higher expense than human. for highest performance, robot needs a high grade parts and have a high price according to moreover robot need repair periodically. unlike human that they just use their ability to work and they can upgrade their abilities by learning which have a low expense. Many companies choose human because they have a low expense to hire and upgrade.