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.