America can't 'ship people to Australia' because Australia wouldn't allow it but under this scheme an American, not an illegal immigrant from Mexico, could potentially join the ADF provided selection criteria was met. It's not a free for all.
As for compulsory service...don't worry, the youth of today won't have their Tik Tok, Facebook and videogame time interrupted as compulsory service isn't a thing in countries like America, the UK, Canada and Australia plus others. Or...maybe you should worry because other countries build armies while our countries build...well, whatever the youth of today are.