I am from the country...rural America.....and once had a log cabin on top of the surrounding mountains....so I am well familiar with the difference between city, suburbs, and rural since I’ve also lived in three major cities.
That said.....all people will steal and take whatever when it’s a matter of survival of their families....including their neighbors. That system also breaks down in time no matter how close.
You mentioning Katrina doesn’t sit well with me because so many in that after fall out were accustomed to being on the ‘generational’ welfare system....highly dependent on Government handouts......and always rage at the drop of a dime anyway.
Might better look at Japan when cities were completely destroyed......different culture mindset and far more self sufficient. There was very little looting and people did indeed stick together. We do not have that mindset in America today.......