Can the Apple store verify my purchase and warranty by serial number

Serial number from device could mean it's been sitting in the warehouse for a year before he purchased it can't it? How would they know his serial number from his device without registering it because I know all the serial numbers show up on my devices but like I said how would the serial number prove that he didn't purchase the device 6 months - 1 year after it left the warehouse or place of purchase. Says on website Apple may require a proof of purchase and to keep your receipt. Also even though his serial number shows on his device they would have to ask him for it. Do they have a way to track a device's serial number by not reporting it?

Yes if you registered your product they should be able to do that but will generally still want a receipt to confirm proof of purchase anyway. Not all people register their products on the website.

Registration is not required for the warranty to be valid, though, just for clarity for anyone reading. Nor does Apple themselves normally require proof of purchase. They can look up the warranty status by the serial number of the device.

Regards.

Serial number from device could mean it's been sitting in the warehouse for a year before he purchased it can't it?

It could, but all authorized dealers are required to report the sale date and serial number to Apple. That's how Apple knows when a device was sold to set the warranty date; the warranty starts on the day the authorized dealer sells the device to the user, not when the dealer receives the device from Apple.

How would they know his serial number from his device without registering it because I know all the serial numbers show up on my devices but like I said how would the serial number prove that he didn't purchase the device 6 months - 1 year after it left the warehouse or place of purchase.

See my previous response.

Says on website Apple may require a proof of purchase and to keep your receipt.

They may, though usually they don't. But again, the user is not required to register the device with Apple to validate the warranty. In fact, in many countries it is illegal for any manufacturer to require registration before a warranty is honored. The proof of purchase is all that would ever be needed, and again if the device is take directly to Apple that's almost never required.

Regards.

Just enter the serial number here:

Apple - Support - Check Your Service and Support Coverage