I've never immigrated to another country, but can someone explain how someone does that and not already have a place to live already established before they arrive?

I can't imagine even travelling to another country without making the appropriate plans for accommodations, let alone move my family without a plan.

I get that some people are leaving some pretty horrific situations in their country and may not have the resources to do that, but we're talking tens of thousands who are showing up with literally no plan and no place to go. This is a worse situation for many!

How is this supposed to work or be sustainable?