Emmie...what if they don't have a passport?...it's been lost, stolen, taken from them by authorities who don't want them to have freedom of movement? Maybe you should try rough sleeping out in all weathers, with other desperate people for company while still holding on to your most valuable possesion(s). You seem to think it's a simple solution, when in reality it isn't. Also, we don't have the ability to keep people out...so how do we "simply" send them back?