It wouldn't help much to send codes, since you could send a code that's different from the deck you were using anyway. (if the illegal deck is intentional) It would only catch the people who are using illegal decks unintentionally.
For example (and maybe RootRanger remembers this) I once used a deck against him in a tourney that was illegal by mistake; I hadn't read the rules carefully and I used more of a certain card (cockatrice) than I was supposed to have. At the end of the game, he said something to me along the lines of "I don't want to make accusations, but it was surprising the number of early cockatrices that you drew" because I'd played the allowable number in less than the top half of my deck, and I had a bunch more in the deck that I hadn't realized was illegal. I rechecked the rules and realized that not only was he right to be suspicious, but that I had used an illegal deck. (and funnily enough, lost the game anyway :p) Basically, what I'm saying is that accidental cheating will probably be caught, either by the opponent or even admitted by the accidental cheater themselves. (in this example, both) A deliberate cheater in my situation would have said something like 'lol, rng', and submitted a deck to the TO that only had the legal number of cockatrices, and some pillars or something else instead in place of the illegal cards.