This strange behavior is existing since the same era with ""Platon"".
But today I'm going to give Great service to you guys and I'm going to solve this mystery in 4 Reasonable Facts. !!!
BUCKLE UP YOUR SEATS
According to my highly effort required researches I found that Storing and producing square shape boxes are fairly cheaper.
It is going to be hard to make pizza circular shape ( not talking about american pizzas) therefore it is going to be hard to fit them in circular boxes.
According to my another opinion it is much easier to take out pizza slices rather then taking out from a round box.
All the pizza makers in the history probably didn't doing it wrong so far so we need to trust them.
Ok guys another strange behavior of humanity Solved today.
Bon apetit.
