Why do I get a better rate if I enter the zip code, CVV code, etc…. ?

We didn’t make the rules, but here’s the story:

The bottom line rates are all based on fraud.
Every year, Visa/MC/Discover get together with card issuers and analyze the fraud rates and see what types of transactions have the highest fraud rates.
They have determined that transactions that are missing certain pieces of information are statistically more likely to be fraudulent.