Hi Gumby, that is something we need to clarify in the TLCA requirements. At Cruise Moab, we addressed this some years ago by having the safety inspectors follow a procedure where the parking brake is engaged and the driver has to rev the engine to X RPM while in drive (I forgot the exact RPM figure) and the truck doesn't move.
<rant>On-topic but kind of a tangent, I have always objected to how the name for this requirement has morphed from "Safety" to "Tech". It is a
safety inspection dangit! This is for participant's and bystander's safety! When I think of "tech" I think of coilover 4 link conversions on 40s and such! Safety is making sure the rig isn't going to be hurting anyone because the brakes don't work or the steering is going to fail!</rant>