Calling a mixture of spicy vegetables giardinara is, as far as I can tell, a Chicago thing, like saying pop for soft drinks. There's two related issues on the table. First, in my experience, other city's subs can also have some type of hot pepper condiment, its just not called giardinara. I remember way back to a discussion of Baltimore hots on Chowhound. Second, the word giardinara is not unique to Chicago, but otherwise, and especially in Italy, refers to a mix of pickled vegetables. It is not that hard to find the more traditional giardinara around Chicago.
All that said, I agree with the sentiment, which I have expressed before, that the general state of subs in Chicago suffers from the nature of most commercial long rolls in Chicago. The soft, dense Gonella roll supports expertly, an Italian beef sammy, but as a sub base, I find it flawed.
Rob