When I lived in Mass, I always thought that Greek pizza was because the owners were Greek.
But I noticed that every pizza shop was named House of _______.
And had Greek people there.
I can honestly say that I have never had a "Greek" pizza.
"The other usage refers to the pizza crust rather than its toppings. Greek pizza (in opposition to Italian pizza) is baked in a pan, instead of directly on the bricks of the pizza oven, and has a thick, chewy crust that is usually quite oily. This style of pizza is referred to as "Greek pizza" even when it has non-Greek toppings, since it is typical of pizzerias owned by Greek immigrants. These establishments often also sell Greek specialties, such as Greek salads and gyros, and tend to brand themselves as "Pizza and Pasta"; a codephrase signifying that it is not an Italian restaurant, but a Greek one serving Italian style food. In the United States, this usage appears to be specific to New England cuisine, although the style of pizza is fairly similar to what is found elsewhere as "pan pizza," for example from the international chain Pizza Hut."