On that note - all documents are immediately expunged from our system upon approval. The only thing we retain "data-wise" is the mark on your account that it's been verified, but nothing from the document itself. The less data we have, the less there is to steal. We don't make money on data, we make money from the merchants paying for the verification service.
You should put a statement to that effect on your website. I gave it (your website) a quick scan and didn't seen any privacy/data collection policy/assurances. These days people are concerned about that stuff.