The concept for zip submits is simple: The advertiser is paying for an "active" customer. That is they propose an offer and they advertiser pays on an action, knowing that if a user enters their zip code a high percentage will MOST LIKELY continue with the process. This model simplifies the payout process and makes the payout easier to track for affiliates. It works better than saying well pay $7 for a fully registered user, or $45 when someone buys. The advertiser could care less about their actual zip code, they are NOT paying for the zip code. Another trick thats involves the user is for loan or other offers with zip submits is geo-targeting. Once the user enters the code it dynamically implants the user's city and "We offer payday loans in New York City." This strategy has proven high conversion rates.
That clears it up...thanks.