I am familiar with hospitals in this context where we had emergency power (generator)which was able to power our equipment but no AC and if that failed we had very large wall mounted battery powered lamps, which gave enough light to be able see so you d/n trip over stuff.
Yes, as far as I know, all cities have safety codes, which I would think would include back-up lighting and generators.
I worked in hospitals some time ago and I know we had to have them. I think I heard somewhere that the SD had it, but it was limited. OTH, I heard it was totally dark in there, so just like you, I find it a bit puzzling.