More and more often, now, if you hand over some plastic in a shop (here in the UK, at least) you'll be handed a keypad rather than a pen. Whether or not this is actually more secure than signing a slip of paper, it's certainly a lot faster and more convenient.
In some shops you don't even hand over your card: instead, you stick it into a slot on the top of the keypad. I can see the benefits of not letting go of your card, at least from a reassuring-the-suspicious-customer point of view, but I have found myself completing transactions without ever making eye-contact with the cashier. As they finish ringing up the total, I stick my card in the reader, and then I stand staring at the little green screen as I wait for it to ask for the number. That done, as the cashier finishes the transaction, I'm grabbing up my card and putting it back in my wallet, and as I'm handed the receipt I'm busy gathering up whatever it is that I've bought.
Now, passing through the checkout is hardly a mainstay of social interaction, but I find myself slightly saddened that even if we choose real-world bricks and mortar over yet another faceless online purchase, we can still get away without acknowledging another human being with a word, smile, or even a look.
Maybe it's a depressing comment on the way our world works, or maybe it's just a thing. But I know that if it was me standing behind the counter, or sitting at the till, I probably couldn't handle an entire day of people who looked at that little LCD rather than looking at me.
Convenience and 'security' will probably win out everywhere. I was in a supermarket a while back that had a row of unmanned tills where you scanned your own shopping and then stuck your card in the machine to be charged. My wife wouldn't let me try out the new gadget, but now I'm thinking that I'm glad. It's not worth it.