I believe that was, "I've worked in the
private sector", not
public sector. I work in the public sector and they don't expect results.
I think part of the reason the movie works so well is that it seamlessly blends humor with horror. That's a potent combination. And it's not like Scary Movie humor/horror, it's legit, crap-in-your-pants horror. The opening library scene was terrifying to me when I was a kid and so was the part where Dana gets abducted by Zuul. That latter scene with Dana and Zuul is still effective, even to this jaded horror fan.* But the laughs really break up the tension and it helps that the humor is so sharply written. Truly they captured lightning in a bottle.
*At night, when it's dark in my apartment, the lights in the hallway of my apartment building light up the edges of my apartment door just like in the Dana abduction scene in Ghostbusters. It's kind of awesome.