There is a big difference between a surface that is provided by an engineer and one that is built for machine control by a knowledgeable model builder. Often an engineers surface is full of errors and not ready to be used in the field. Engineers build their surfaces to create paper plans not machine control models.
As a company with seasoned and knowledgeable model builders, we build machine control models that are error free, easy to see and a breeze to use in the field.