Saying that people should go to prison because they happen to illegally be in a country that’s not theirs is in the same realm of bad things as what the mainland Chinese are trying to do now in HK.
Illegal immigrants are not sent to prison unless they committed additional crimes, usually they are deported and sent back to their respective countries.
Right. Not prison ... "detention centers". In which they will be held against their will sometimes for months or years and at times with even fewer rights than a traditional prisoner might get.