Why shouldn't illegal migrants be jailed - sure they can leave their own country - but they have every intention of entering some other country illegally and imposing a financial burden on law abiding taxpayers.
If they make it into Australia in this manner they should be locked up with only one way of being set free - going back in the direction they came from - I don't care about the problems of the Middle East or Vietnam, which has been at peace for decades. They are nothing more than a bunch of opportunist freeloaders.
