The tariff is certainly set by the site owner, and although I have no knowledge of the actual contracts it seems extremely likely that the site owner is paying for the electricity (in all cases - they then set the tariff to make the money back if they want to).
Nearly all the PodPoint sites appear to have been installed by way of a 'customer/visitor perk' by the site owner. The recent Tesco/VW ones are more interesting as they appear to be intending to actually make money out of it: by putting in multiple rapids and charging a commercial tariff on them, plus slow chargepoints at no user cost but sponsored by VW/advertising.
(note that you need multiple rapids to have any hope of making money out of them, since a single unit can only support such a low level of demand that no plausible tariff could ever pay back the installation cost. Two units can serve much more than twice the demand, four units even better).