Emergency power generation is common onsite for datacenters, even if it is not supposed to run for long time. And I think you are overestimating the redundancy. There was famous infamous "I can't find such option in admin panel" response to news about total loss of Strasbourg datacenter in March 2021 fire, after advice to "execute Disaster Recovery plans". And I doubt it got much better for small companies. How many people even run backup servers in other cloud regions/countries, not just different AZ?