Not sure about the US, but shelters here are generally owned by the local council (mostly school gyms) and there are pre-made agreements for emergencies. That part isn't the issue.

In some countries, the government will just ban people from going to work. This takes the paycheck issue out of the discussion. Unless you are part of the emergency or recovery crews, you are not going to work. This works better in places where most have fulltime employment and the employer will just pay full wages, with or without deduction of vacation days.