To add to this, backup power systems are in fairly widespread deployment and bigger installations are tested and maintained on a schedule. You'll never see "hospital transferred emergency-available circuits to backup system; no malfunction" in the news, yet it happens every few weeks in every installation.
Generators themselves are very reliable machines. The engines are cast iron (instead of cast aluminium as found in all cars since two decades or so) and are nowhere near as close to the edge of material capacity compared to car engines. Electrical generators are essentially just a big blob of metal, they are simple, efficient and very reliable technology giving many decades of service. Generator controllers are designed to be reliable and aren't terribly complicated, either.
If generators really are just a giant blob of metal and very simple (and I have no reason to disbelieve the GP comment)... well... it could be kind of interesting to build an open source software stack to handle switchover. Because, disclaimers notwithstanding, the code would ostensibly be super simple too. So even if it couldn't officially be used directly, it would certainly provide a good base for engineers to copy-paste, either literally or ideologically (and then thoroughly verify, of course!).
Okay... thinking about it, I'm probably wrong - either generator control has some fundamental intricacies that make it not-completely-simple, or all sites have edge cases that have to be baked into the firmware by a system integrator/electrical engineer.
I say this because I'm (genuinely) trying to figure out why the PLCs failed - both in OVH's case, and in AWS's case (see elsewhere in this thread, https://news.ycombinator.com/item?id=15676189).
It's obvious there are crazy but legit reasons for this kind of thing to happen. I'm very curious what the complexity scale here is.
The actual diesel engines and generators are simple metal. Not the switching circuits. If the electric controllers can't handle the load/switching speed/whatever, no clever software and/or reliability in the actual generators will help.
I've seen what switching 20kV looks like in videos - yeah, that kind of thing requires very careful design, and is invariably going to come entangled with a PLC-style controller, as is the norm for industrial equipment.
Generators themselves are very reliable machines. The engines are cast iron (instead of cast aluminium as found in all cars since two decades or so) and are nowhere near as close to the edge of material capacity compared to car engines. Electrical generators are essentially just a big blob of metal, they are simple, efficient and very reliable technology giving many decades of service. Generator controllers are designed to be reliable and aren't terribly complicated, either.