Why are pizza's packaged in a square boxes when the pizza is made round?

Because is cheaper to make a square box. There's a lot less retooling necessary when the company switches from pizza boxes to some other type of box. It's also easier to get the pizza out of the box

This is opinion, not fact. But I think it's because it is easier to get the pizza out the box. You can pick it up from the corners of the box where the pizza doesn't touch the sides. If the box were round you would have to tip the box upside down for the pizza to fall out.

Because square boxes are easier to make.