the magnetic strip contains any personal information. All that information is housed in the casino's database where they can use it. Your card simply has an account number on it. This account number is used to reference all your personal data from their database.

If you don't have access to the database, you can't abuse the data.

Likewise, your point totals and stuff aren't stored on the cards. The slot machines have card READERS, not writers in them. All your comp information is stored in the main database. And you can't "steal" anyone's data, because you have to have a picture ID to redeem the points (in person) for comps.

At least this is my understanding.