I half-remember an article I read a long time ago about chip and pin cards that mentioned asynchronous communication with the mothership as a big win for the chip.

The example it brought up was that because the chip's identity could be verified through local communication with the chip, purchases could be logged at the terminal and synchronized at any point with the payment processor.

Is there something about the US payment processing market that makes that feature unattractive? Are businesses subsidizing more fraud protection than in other countries by making transactions synchronous and hiring more staff?

What do you mean cache the swipe? You can swipe and have a receipt in your hand before the chip cards tell you to remove your card. They are simply way slower. NFC is similarly speedy in comparison to the chips.