"More than 70%" does not mean "More than 70% have their own driveway".
Apartments don't have driveways and underground garages are often hard to retrofit.
I used to live in a block of flats with, I was a director of the management company. We nominally had 1 parking space each, but it wasn't allocated.
We looked into putting in outside sockets, it was fairly low cost, the difficulty would be apportioning the metering as we didn't have allocated parking spaces, but with allocated parking spaces it's not a problem.
On my own housing estate in a typical British town almost every house has a drive. Those with two cars and just one drive that park 1 car on the drive and one on the street, but that's fine, just swap them occasionally (or better yet get rid of the extra car)
I can't think of seeing underground parking anywhere in the UK, other than commercial ones in cities like NCP etc.
> "the difficulty would be apportioning the metering as we didn't have allocated parking spaces"
There are already various technical solutions to this. Most chargers now days are "connected" - ie have a WiFi chip or cellular modem built in to the charging unit. Identification/billing can be apportioned via a RFID card or app interface.
In future, "Plug & Charge" will make it possible for the vehicles to securely identify themselves to the charger for automatic billing, doing away with the need for an app or RFID.
If cost of the chargers is an issue (ie you want a large number of outlets but it's initially split between only a few EV owners who are willing to pay for them), then consider something like Ubitricity (ubitricity.com) where the outlets are "dumb" and the billing smarts are built into the cable which EV owners purchase.
73% parking on private property doesn’t mean 73% have their own driveway, and it was only mentioned that it’s cheap to install a charger in a fairly recent driveway.
I suppose GP’s question is how does that 73% figure change when you look at people who can realistically have a charger installed in their parking spot.