Region to Region - town to town
Yeah, Italian cooking is almost a misnomer since there is no one "true" Italian style. Most of what we know as "Italian" here in the US is the food from Emilia-Romangna which has the town of Bologna in it, which is considered the culinary capital of Italy. Think rich, hearty Bolongese sauces - almost a "Rococo" style of cooking as flavors are layered on in heaps and bounds.
But is that "Italian"? Yes and no. It is a type of Italian, and a very good one at that. But if you head over to Tuscany, the flavors are simple, clean and pretty much one to a plate by comparison. Heck, they don't even use salt in their bread in Tuscany, which I personally find inedible...
But the point that you use what you have in front of you, or available, is an apt one when considering how Italians eat. Since the history of Italy is not one of a unified country, but rather one of individual city states that were only recently (in the grand scheme of things) unified, each region developed its own cooking style, and sticks by it fiercely.
I taught a class on "Northern Italian Cuisine" once, and found it to be a tough topic - I had to limit which regions I dealt with if only because every time I added a new state, there was a whole new cooking tradition to take into account. A great book that talks about regional Italian cooking, and deals with each region individially is "Italy, the Beautiful Cookbook" And, yes the pictures are quite nice as well.