[* ] I've only once in my life ever had to sign for a transaction, it's not a common method, I just mention it here because I know some countries still use it.
Apple Pay doesn't really compete with Contactless - they are the same thing! Any merchant that accepts contactless therefore accepts Apple Pay as well, whether they advertise it or not. (Here in the UK, at least)
Apple Pay is a bit more secure because transactions are authenticated with your fingerprint via Touch ID, and the merchant gets a special device card number rather than your real card number. But as far as the payment terminal knows it's just like any regular contactless card.
Whether it's more convenient to take your contactless card out of your pocket/wallet, or use an Apple Pay device is a matter for debate. I find that I usually already have my phone in my hand while standing in a checkout line, so I pay with that rather than fumbling for my card.
If your phone can do everything that your card can do (and a lot more!), why carry the card?
(I also print out airline boarding passes unless it's not convenient to do so for some reason. I'm not fanatical about it, but if it's just 30 seconds of effort, I figure that I might as well.)
It's also more secure because you're authenticated by the fingerprint scanner, and it's anonymous.
There have been several times I've got stuck behind someone using their Apple phone to get through the gates on the London Underground and have noticed two or three people get through the gates on either side in the same time as the one with the Apple phone. And it isn't just me - according to http://www.theguardian.com/technology/2015/jul/16/tfl-cautio... the iPhone "has led to irate commuters and queues at the gates".
The transaction will stay authorised for a couple of minutes, at least, and then the gates will open nearly instantly when you put your phone near the sensor.
This isn't an issue for using Apple Pay via the Apple Watch, since that device skips the Touch ID requirement (instead, it will de-authorise if you take it off your wrist).
no it's not.
I probably make most of my purchases with a very small group of retailers - for example, in terms of number (not value) of transactions, the sandwich shop by my work and the corner shop by my house probably account for 80% of my offline transactions. (I go to the supermarket about once a week, and although I tend to buy more, that's all in a single transaction.)
If you could sign up those merchants, and give me a compelling reason (convenience, discounts, rewards) to use your payment app, it might not matter that I couldn't use your payment app on those rare occasions that I go shopping somewhere else.
Just a thought. (I'm not in the payment industry.)