A friend's brother owned a construction and landscape company. One of their key philosophies was "You have to know how to write a bill." A wide range of equipment types, each with different hourly rates, can be used on any one job. Different procedures can be used. Figuring out the combinations that create the greatest "defensible" profit was a widely acknowledged goal of most companies in the space. I am also aware of training companies that do something similar.

It's a common business mindset, unfortunately.