I found https://www.racfoundation.org/research/mobility/still-standi... a fascinating report, especially how nearly half of London has off-road parking.
https://www.racfoundation.org/wp-content/uploads/2017/11/spa...
Flats and terraced homes aren't the majority - about 55% of people live in detached or semi-detached houses. See the ONS Census data at https://www.ons.gov.uk/peoplepopulationandcommunity/housing/...
My terraced house has off-street parking, as do most of them in my area.
Houses with separate garages are also fairly easy to upgrade - we had an armoured cable buried in a new trench to connect our old property.
Similarly, most flats with car-parks are especially easy to add chargers to. They can either be 7kW points or just regular plugs. We had slow chargers installed in our old flat.
Yes, there are many properties with no easy way to add charging. But none of those places have a petrol pump attached either.
But since you can plug in to charge at many street lamp posts and since most people don't drive their cars much on a day to day basis, it all works fine even without off-street parking. There are also several reserved medium-speed charging spots around the neighborhood and lots of fast chargers at the local large grocery store.
Are these the standard UK 230V 13A fused single-phase receptacles? Those put out about twice as much power as a 120V 15A circuit protected by a breaker, 3kW vs 1.5kW
230 * 13 = 2990W
120 * 15 = 1800 * .8 = 1440W
Using those for L1 charging would be a lot better than US L1 charging.
But you are right that standard wall charging is much more viable in a 230V system here than in the US. Some people just run a cable from inside to their car if they don't have a 'real' charger yet.