What’s with the hold up in mobile NFC payment options?

There’s been much talk of the possibilities of using NFC to pay for things in-store, but there seems to be a general lack of options available. So what’s the hold up? Mobile payments is a growing industry, and it’s a confusing one at that. While using your phone to make a bank payment or even browse eBay are fairly common mobile payment options, using your phone to get through the train turnstile or pay for a coffee still, in general, seems like a fairly alien concept.