You're right, of course. We can get sloppy if we paint our strokes a little too broadly, and it's always a good idea to think critically about the received Roman political categories and terminology. On the other hand, revisionism can tempt us into over-correcting, as I think is happening here:
Whether or not "Samnite" was an autonym (and it may well not have been), the various tribes of Samnium did in fact work together politically for large stretches of what we know of their history. No doubt they weren't always unified. However, they signed treaties collectively with the Romans, founded political leagues operated from a capital city, worked together first in military opposition to Rome and later in multiple uprisings against Rome. In face of this, saying "there was no such thing as Samnites" would seem to me to be rather difficult to support. Even the question of whether they called themselves Samnites likely has no single answer; the political terminology of dominant groups like the Romans has a way of become reified over time, so that what was an artificial imposition in earlier generations becomes the accepted reality of later ones.
(EDIT: It occurs to me that part of the problem here is a confusion over the word "tribe." Whatever they were, the Samnites certainly weren't a "tribe," but that's not especially relevant. Neither were the Romans, after all, nor the Etruscans. The peninsula had plenty of supra-tribal political entities.)[/qoute]
Yes, the "Samnites" did work together for against Rome for long periods, they also went to war with each other for long periods. The issue I was bringing up is that Roman history is often see as the only history. Now, this is often a good thing, rich sources ect. However one must often consider the other versions of history.
The point I was making is that while the Romans referred to the people of Italy as Italians, the people of Italy themselves did not. If you will note my first post, I said "to a lesser extent", because, of course, we do now have Italian people. However it was a very gradual transformation, spanning many centuries.
You are right when you say "Italy didn't exist" is a load of rubbish. Of course it did! It was there, much the same as it is now. A nation of Italy did not exist, but the landmass did.
Many scholars, including myself, put the first unification of an Italian Italy in the early 1800's.
However, I think there is room for you point about dominant political terminology. By the middle of the third century BC there was only one law in Italy and that was Roman law. If the Romans said you were an Italian did that not make it so? Yes and no.
History many now have these, incorrect, catch all names like "Latians" "Samnites" and "Italians" but the Romans also used "Gauls" "Germans" and even "Barbarians". None of these people considered themselves so. Yet that is how, much, of history remembers them. Does that make it right?