I don't agree with your opinion that robots can save labor cost.

You said that robots don't need to take a rest, get paid wages and have a meal, just charging the battery. However, It costs a lot of money to manage robots instead of providing wages and meals. And applying robots to work will cost a huge amount of money for initial production. Also, If a robot breaks down, it will cost more than a month's salary. Because, robots are not yet common, so they are very expensive. 

In conclusion, I argue that robots are inefficient in terms of cost.