Why would the media show a whole bunch of plastic guns and act like they're real?

Question

The kind that shoot plastic pellets.

Answer 1

I assume you are referring to the cache of weapons seized from the home of that 14-year old boy in Montgomery County, Pennsylvania. I read the reports on the local CBS affiiliate's news site in Philadelphia and downloaded some of the video as well. They clearly indicated one of the weapons was a 9-MM assault rifle and the others were air guns.
But, since one of my sons was shot in the eye by one of those "plastic guns" many years ago and had to undergo delicate surgery to save that eye, I would hardly call such a weapon not real.