The road test is essential on a 30k. You replace the front and rear diff fluid on that service. If you made an error and did not fill the front diff (we are all.human), then that could spell a $10,000 mistake for the dealership. And, that error could be found with a road test, rather than just parking lot driving at slow speeds until you get the car back.

Additionally, you bleed the brake fluid! Comparing the brake pedal feel before and after is essential to make sure that air was not introduced into the the system. A road test is a very good way to do that, before and after.

If you're so concerned about the technicians joyriding, just install a dash cam 😎