Where are you from? Around here (Southern California) every card reading machine defaults to debit transactions, where you have to enter your PIN anyway. At least when you do credit cards you don't have to sign them for small purchases any more (less than $50 at Home Depot, for instance).
I really can't say I've ever felt frustrated waiting for the person ahead of me to pay (except for maybe old people hand writing checks at the grocery store—and even then it's kind of interesting to see such old-school payments in action).
Debit or credit? Debit is the default everywhere. Why? Because credit has a surcharge for the merchant.
It is complete bullshit that the merchants put the onus on their customers and then shrug their shoulders when fraud happens. At least with credit you are insured. They get your pin and you are screwed.
I've never used a contactless method. Is it NFC (or something similar)? Is it really faster than swiping your card? I had the impression you still had to do something on your phone to authorize it...
Even in 2007 in Denver, Amex issued me a credit (not charge) card with a little RFID chip. Worked at a fair number of places. Just get the card near and it beeps and you go on your way.
I really can't say I've ever felt frustrated waiting for the person ahead of me to pay (except for maybe old people hand writing checks at the grocery store—and even then it's kind of interesting to see such old-school payments in action).