If they have not been hit for a century, it remains to be seen how well the existing kinds of flood defence will work out. Have they done anything to strengthen or at least maintain them since then?
It's almost definitely worse, more development means more covered land which means more water flowing faster to holding areas, that likely aren't sized for the amount of developed land.
Why spend their own money, when they could just wait for that sweet federal money after a disaster? (While blaming the federal gov and being completely insufferable, ungrateful cunts.)