Declines: CVV Code & FRISK

We've been taking credti cards online for years for recurring payment but recently noticed an increase in declines.

We studied our declines talking with our ISO and found that for international credit cards, the card companies are increasingly declining them unless the CVV code is given.  We have always NOT required a CVV code since fraud is our industry (online education K12) is nearly non-existent.  Looking forward, since we can't require a CVV code on transactions without forcing all of our monthly transactions to fail.  It might be possible to only require CVV on new credit cards via the ISO software. But the easiest thing seems to be to require CVV on our shopping cart and so for all new credit cards, we start getting it. This will prepare us for a future where credit card costs for non CVV coded transactions might go up or even get refused.

FRISK (Fraud & Risk Management) . Notes on three types of FRISK Credit Card declines.
- duplicate transactions
- AVS - address verification
- CVV2

3% back on gas puchases

I've been seeing a lot of affinity credit card ads on TV lately which promote a percentage rebate cash back on certain purchases. The most striking to me is the 3% back on ALL gas purchases. Can anyone explain to me how anyone makes money on these arrangements?