I have seen this happen with a building across the street from where I lived. There were 5 large men who could have easily been bouncers in Oakland outside with "FueraOkupa" shirts. The woman left later that day.
I live in Spain (Valencia) and see lots of okupas around the city. In reality they occupy buildings that aren't being occupied. Property taxes are incredibly low here and many people who own empty buildings are fine with letting them sit, fall apart, and eat the property tax than do anything with them. These are the buildings that are prone to Okupas. I've never seen nor heard of it happening to actively used buildings.
That said, I do think there are better solutions to allowing this to happen. It's a complicated issue here as housing is definitely viewed more as a right than in the USA, and honestly I'm really glad that the streets aren't full of homeless camps like they were when I lived in Oakland and SF.
Not all of that capacity in the interconnection queues are ready to flip the switch though, correct? Requests can be pre-construction, construction, built/non-operating, and operating [1]