I mean, I kinda get where the Italians are coming from with this one. Dishes have a "soul," if you will, in that you can vary the ingredients but still get to something people can recognize as that dish. "Hamburger" is minced meat between bread, for instance, but within that range you can still create infinite varieties that can be called "hamburger."

It sounds like pizza marinara's very definition involves not having mozzarella... So asking for marinara with mozzarella is probably asking for something which, in essence, isn't marinara. Imagine someone asking for "hamburger in a hot dog bun"... We'd probably tell him "OK, but that's a hot dog, not a hamburger."

Really, I don't think it's just an Italian thing.

A dear, dear friend of mine upsets French waiters by asking for her meat to be 'very well done'. Through clenched teeth the waiters explain that the chef will refuse to cook all the taste out of the meat; they have standards to uphold. My friend ignores their obvious disdain and asks, 'But it will be cooked properly? Not a hint of pink?' They seethe and mumble unkind things about expecting nothing else from a nation that boils vegetables like their washing, while I try to salvage international relations by ordering my meat sanglant.

I'm going to have to side with the French on this one. A well done steak is no less than an abomination unto the LORD. At least it should be. The fact that the Bible says nothing about a well done steak being a sin throws some serious doubt to its credibility.