Gosh, I could never put all my eggs in one basket (my iPhone).
I use Apple Pay when I can, but still carry physical cards. (What if my phone dies, or gets lost or stolen?) It's also nice to be able to disconnect and leave my phone behind sometimes.
I also carry some cash as well since it doesn't take up much more space. Has no one ever run into an instance where a merchant's payment network is down? It has happened to me several times in the past few years (at a major retailer, car wash, and at a restaurant). Cash saved the day while nearly everyone else abandoned those places.
Both actually work pretty much the same. Cards do transaction-specific, one-time codes as well. The NFC terminal powers the chip in the card to generate the code.
Apple Pay just takes this one step further by using a virtual card number, so that your actual card number isn't stored on your phone. This is mainly for security, and so that you can easily disable your virtual card in case your device gets lost or stolen. (Otherwise, if it used your actual number, you'd have to disable your actual card and wait for a new one.) Apple Pay doesn't generate a new card number per transaction. You're probably thinking of the one-time code that's used for the transaction, which cards do too. If you look at your receipts, payments using Apple Pay should have the same virtual / Apple Pay number that's shown in your Wallet. Also, when you use Apple Pay via NFC, Apple is not involved at all during the transaction. (Using Apple Pay on the web and in apps is a different story though.)
Here's a couple links from Visa and Amex that go into a little more detail about how contactless payments work with cards.
Tap to pay with Visa for a secure, convenient, and touch-free way to make transactions anywhere you see the Contactless Symbol.
usa.visa.com
Want to understand contactless payment and how contactless cards work? Read our article about the benefits of going contactless with American Express® now.
www.americanexpress.com