Of course if it really is 5 people watching the one guy put of cones that is waste. However most constructions jobs are let the machine work for 10 minutes, then you need 5 people for manual labor for 5 minutes before the machine works again. While it is true you have 5 people standing around watching the machine work 2/3rds of the time, there is nothing else that they could do and be back in 10 minutes so it is most cost effective to pay them to do nothing 2/3rds of the time.