Any organization that provides a service such as transportation or any type of field service has experienced their customers challenging them about having actually provided service. It could be any service from cleaning to servicing a bus stop to pick up passengers, but whatever the service, organizations get challenged and they have no way to defend the customer complaint.
When the customer complains and challenges the service that you provided without your organization having any proof to show your customer that the service was indeed provided, you are stuck with somehow having to make it right for the customer, either with a refund or by redoing the service. Whatever the outcome, without some record of the fact that you did what you were supposed to do, you are in bad situation. You may also be in a situation where you have an employee doing exactly what they should, but who basically becomes demoralized and feels upset that a customer is complaining. You do not want to lose good employees due to these complaints.
With GPS tracking technology, you have the ability to show your customers when you arrived at the job site, how long you were there and when you left. If there was any on-board equipment involved to perform the service, you can show them that the equipment was indeed used and for how long. With GPS tracking technology, there is absolutely no question about the ability to demonstrate proof of service to your customers.