rework, warranty (used trucks), and mistakes can be billed back to service and sales like any other customer
you take those and claim them as losses

not only that standing behind your work (as a company) when there is a problem reinforces you commitment to quality which in turn makes the company more profitable through customer retention

if a techs failure rate is so bad that its cutting into the bottom line, how long will you really have to worry about that guy being around for anyway?

as a person who has intimate knowledge of his area (METRO NYC) i could tell you how long it will take you to get to point B from point A within 5 minutes factoring in time of day (10 miles can take well over an hour around here in a commercial van)
GPS is for the suits who dont know how far A and B are away from each other what roads to take and what traffic to expect