Whole building GFCI - that is just nuts!
There are many ordinary motors that will leak just a bit to ground, enough to trip the GFCI, but no hazard exists — this would mean disabling the whole building, computers, refrigeration, water pumping, etc. just turning on that device. I've actually got one in a treadmill, and also a wood router tool - they trip the garage GFCI every time. At first I was concerned and "what's wrong with these things?". but as far as I could read, there is no issue, just an issue with certain types of motors that is no hazard, but a basic incompatibility.
And yes, being able to kill the entire power to the house merely by plugging a device into one of the outside outlets would be an insane vulnerability, not just by the contractor's accident you mentioned, but also by deliberate action - great way to start a burglary or home invasion, don't even need to find a wire to cut.
Yikes!
A whole building GFCI sounds like a bad idea, throwing the entire house into darkness as well as cutting off the refrigerator and HVAC because a contractor plugged in a damp power tool in an outside outlet sounds like a bad idea. Worse if you were out of town when it happened.