For cases like New Haven Style pizza and some of the original NYC pizza places like lombardi's, they use coal ovens which get really really hot but don't really

For cases like New Haven Style pizza and some of the original NYC pizza places like lombardi's, they use coal ovens which get really really hot but don't really have a flame like wood oven. So you end up cooking them longer than in a wood oven, which makes them crispier but also a little charred around the edges. Given that these places served a lot of immigrants when they opened, I also wouldn't be surprised if it helped having a sturdier pizza that you could take to work with you.