To play devil's advocate, paying some dudes to haul diesel for a few days every decade might be a lot cheaper than maintaining a fully redundant failover site 24/7.
They don't get paid extra. They're just expected to give up their free time and risk injury doing something they weren't hired for so bosses get a bigger bonus. (you also don't need a fully redundant site to maintain business continuity)
A just a single day of labor would pay for a fuel pump and line so nobody has to carry fuel drums up a staircase.
Im all for doing some dirty work when needed, but if they expect 100% uptime they should be ready for something as common as a storm flood without risking injuries hauling fuel drums by hand.