"why can’t people just be tourists and return home after their stay?"
To answer that question, one only needs to travel to where they come from for an eye-opener. That Mumbai train station example I posted earlier is just an example of reality that people will not understand till they actually go there and objectively compare how lucky we have been!
It's such a shame that they've opened the floodgates to completely useless people from the sub-continent and other parts of the world.
