If u have tracker in your van proshadetree all it means is the lazy guy wont sit at the side of the road he will sit on the customer site and kill time that way doing nothing and yes your right the lazyones do have a good abilty at writing there timesheets out to make them look as if there were busy we can all do that if we wanted but at the end of the day the manager that is closing down the jobs should be able to spot the pattern and no roughly how long it takes to do jobs in different enviroments.In a lot of cases the manager is probably aware of the lazy ones but its ok saying get rid of them but how long will it take to replace them.
If you think u have problems we have one guy at our work will go to break down be there 2 days later for a simple breakdown that would take good engineer 2 to 3 hours to fix and he gets away with it all the time were i come from it can take months to fill a engineers position