Do you know of any known public example of someone who has actually done that? This seems advise similar to eating 6 portions vegetables a day: everyone says it's critical, nobody is doing it.
In all the cases of Amazon and Google Cloud outages I've seen that were beyond a single zone, it all hit the high-valued companies hard. I've never seen anyone declare that they decided to activate their alternative provider where they have a continuously updated copy of all the data so the data loss is minimal.
Everyone is just assuming Amazon or Google will fix it and that any data loss from activating a non-hot standby is not worth it.
I don't know of any public examples where someone made an emergency switch from one provider to another. I doubt it's happened often, mostly because multi-region failures are so rare. Like I said, if your infrastructure is at all complex it's very difficult to keep it portable. I doubt any "high-value" company would be able to make an emergency switch without their downtime exceeding what they would have experienced if they just stayed put.
There's products on the market dedicated to abstracting clouds for using more than one or switching easily. I'd be shocked if there weren't companies using them for the former. Those most concerned with availability usually just avoid clouds, though.
In all the cases of Amazon and Google Cloud outages I've seen that were beyond a single zone, it all hit the high-valued companies hard. I've never seen anyone declare that they decided to activate their alternative provider where they have a continuously updated copy of all the data so the data loss is minimal.
Everyone is just assuming Amazon or Google will fix it and that any data loss from activating a non-hot standby is not worth it.