They may need arrange hire of an off street location for an hour or so. Or spend the time finding a place suitable (110kp\h zone out of the way).
Then cost of their time to do the test required and the time it takes to write and submit the report.
In SA there is something like 15 repeated hard stops from 60kp/h one after another to test fade. Then 2 from 100kp/h to test effectiveness. During the test the car must not fall under a certain g-force or have any undesirable characteristics or else it fails.
Engineering is a highly skilled profession, so expect the rate to be $100+ per hour.
FYI the rolling test at inspection is a bias test. The engineers test is an effectiveness/efficiency test.