McDonald's Self-service

  There is a McDonalds near my home. It is open 24 hours. In the past there were 4 service lines for ordering food. Recently, It cancelled 2 services.There are 2 services lines left and recently they just installed 2 self-services.At begaining it is inconvenience. The line is longer than before. I calculated a staff's salary and found the reason is that McDonalds will reduce payroll.

  If a service worker's salary is $12/hour and a worker works 8 hours per day. His income is almost $100/day . Then,this restaurant should pay a staff $36500/year. I only accounted 8 hours not 24 hours.
The cost of the self-service machine, I think, is maximum $36500,because It should not be expensive than a car.
Now,the restaurant bought 2 machines to replace 2 services workers. This machine can use many years.  In the future, it will save two staffs' salary $73000/year at least. However, two job lost.

Unlike China, the salary of Canadian is much higher than that of China. In China, a worker's salary is about 100 yuan/day and is about $20/day. So McDonald in China doesn't need to buy machine.