Anywhere there is large amounts of standing water should be evacuated until the water is away from the homes.
I know what just 3 days without electric is like and it grows old ‘very fast’ trying to work around that....and my building wasn’t flooded nor was it in the heat of a major crisis.
That standing flood water is dangerous. People will fall sick from all kinds of pathogens and exposure to toxins. They also risk their future rescuers’ lives even more at that point because they will likely be contagious.
The power has to be cut anyway due to risk of electrocution and fires, but, you are right, living without electricity in a residence that is not designed to be off grid reduces you to a third world state pretty quickly. I went only 4 days with down power lines a few winters ago and I still can’t believe the state my house got into in that short time.
BTW, thank you for all your contributions to this thread. The photos are excellent.