The fact that you do not have to pull a card or even your phone could make the transaction faster.

Except they didn't in the real world.

The only place I ever saw these was at Whole Foods, and the store's POS terminals don't let you tap or palm until all items are rung up and there's a total available.

Usually when the cashier is down to the last two items, I have my card already out and hovering over the chip reader. The transaction completes in under two seconds.

Palm scanning is slower than any payment method other than cash or checks.