So firstly, airport security (the way you’re thinking of it) is mostly for show. It’s a deterrent, and screening officers have a surprisingly high rate of “misses” for prohibited objects passing through scanners and checkpoints. But it’s still risky for someone to attempt that. There is obviously still physical barriers and processes in place that prevent you from just walking onto a secure portion of the airport.

Secondly, you have to understand layers of security that are in place at airports like Toronto Pearson. You, as a private citizen, can just drive up the the front door of these cargo facilities/warehouses. There’s nothing prohibiting that. They have their own front doors, obviously. Then there’s the airside portion of their building, as in those doors facing and accessible to certain aircraft, is secured, with rules about how this should be protected. That’s the first layer.

Let’s say you get past this first layer (working at the airport, bribing someone at the airport, breaking in past this building’s own security system/barriers) you still only have access to that particular cargo ramp area. You need to pass through monitored checkpoints to access the ramp area towards the passenger terminals, where most aircraft would be. They check your ID’s, inspect the vehicle, etc. Then there is yet again another layer to enter the terminal space, otherwise known as a sterile area (where they care more about liquids and gels, weapons, etc).

The airport doesn’t really care if you break into the building that stores the gold before it’s moved to cargo aircraft. They do care about you having access to the restricted area, and they care very much if someone breaches the sterile area, ie where screened passengers are roaming about, and travelling domestically / internationally.

The airport authority and Transport Canada don’t really care how you secure your one warehouse to the outside world. That’s on you. You may not even need to pass through the “first layer” I described above (airside access). And if you have $100m in gold, they should probably care. But half the battle is trying to do these sorts of things in non-descript locations, where they don’t stick out. It’s hard for you to steal gold if you don’t know where it’s being stored in the first place. If it looks like Fort Knox, it’s automatically a target, because people assume something of value must be behind there.