After doing a bit of reading, the issue is just the air brakes. Semi air brakes are engaged by default, and use air pressure to disengage. If a rig dumps the air pressure in the brake system, all the wheels are locked. There are three ways around this: 1) fire up the truck and disengage the brakes, 2) the really big tow trucks have lines to hook into air brake systems to disengage the brakes, 3) brute force - there’s only so much friction between the tires and the road, and it can be overcome.
So, basically all you need is the key and someone who knows how airbrakes work. Of course, at that point you can probably drive the truck to the impound lot rather than towing it. Surely somewhere in the ranks of the RCMP, OPP, or OPS there’s someone with a commercial drivers license.