I like and prefer your format. No matter how say "Ecotricity" play their cards, your your open system would be preferential to me.
Just had a look at their site. Conditions, maybe's and choices ...
Register here to get an Ecotricity swipe card and you can start charging your car at any of our charging points across the country. If you're not an ecotricity customer then you are only entitled to the first 12 months free, after that we might charge £10 a year (but not for the electricity you use).
If you are an Ecotricity customer (or become one in the next 12 months) then the card is completely free for the indefinite future.
Our top-up zones have 13 amp 3 pin and 32 amp 7 pin connections designed to charge most vehicles. Over time as technology changes we may upgrade these.
As EV's become more in use then I can see very slow queues forming to charge up at these major locations. Once you have a keycard after the next year they can place the electric on your own bill! I guess if you are thinking of getting an EV. It's an option to lock people in to their supply. Or not if the first 12 months then £10/yr's use will be made of them.. ... I'll take that as being an individuals choice and off topic.
Sadly it's going to end up like disparate maps for Shell, another for Tesco, another for Texaco, another for Q8.... And the guy who prints the lot gets his page saved.
A downloadable file/webpage with overlays to tick out the key card suppliers and plug types will hit the sweet spot with users. Ecotricity won't be doing that because they have a vested financial interest in it. Plus the fact they have so few charging locations they don't need a map!