I am confused, they are angry what the American government has done to them.

What were they supposed to do. Canada will not let them reenter, they had been denied entry to the US so it is not like they were going to just release them to run around the US after illegally entering, and the UK is being slow about the deportation. The family is still together and they didn't remove the child. Were they supposed to be put in a 5 star hotel?

People complain about the condition when they illegally cross into the US (I am from southern Texas and have a lot of exposure to this), but just image the conditions if you got caught illegally crossing into say Russia, or China, or Iran.