Why would anyone do this?

Here's my two cents- There's a very good chance that this isn't a Roadrunner but a Belvedere or Satellite with a Roadrunner hood . The grille isn't blacked out so its off of one of those model cars anyway . Years ago I had this old beat up 318 powered 4 door Belvedere ; the front had been hit so I bought a fenders grille and bumper off a 68 Roadrunner out of a junkyard, and later had a Roadrunner trunk lid as the original was bent. You'd be surprised how many people thought it was a 4 door Roadrunner ! That , and looking at the very dated looking custom paint job, it may have been built in the 1980s when these cars were more plentiful ,especially down south and out west. Not that it couldn't be a real Roadrunner; back in the early 80's we chopped up a 68 Super Bee to re-skin an old Dodge Coronet bodied stock car my buddy had !