Making paying for electricity at EV charging stations as easy and "friction free" as possible is very important. Not only does it removes a barrier to adoption for would-be electric car owners, but it will also mean that more charging stations will be built. The cost of electricity is low enough - compared to gasoline - that some business owners will offer free charging as a loss-leader, hoping to attract more people. But hoping that enough places will just give away electricity isn't enough... Figuring out ways to ensure that, if they want to, people can build charging stations and they'll make some money to pay back for the installation and electricity costs will do a lot to increase tremendously the rate at which new charging stations are built.
GE, which makes the WattStation charger pictured above, has partnered with Paypal to try to simplify payment. All that EV drivers need to do is to have a Paypal mobile app on their smartphone. Once at the charging station, they scan the QC barcode on the station, which identifies the station and the pricing structure. The power is then paid to the station's owner via Paypal with minimum hassle (hopefully!). The app can also help locate charging stations.
Seems like a decent way to do things, but since there's an important network effect in play, how useful it is will depend on whether it is adopted widely and becomes a standard or if something else becomes the way to pay. Maybe people will end up just swiping credit cards?
Here's a clunky corporate video that tells us a bit more about the WattStation: