With regard to the Camp Bastion example, electric vehicles may have had an application for all the on-camp tasks. Its usually more efficient to have one diesel generator running at max load and efficiency and full operating temperature, than smaller engines being started and stopped, whilst they are still nearly cold. The cost in time and lives to get fuel in made it a much more valuable resource than at home.
The Camp Bastion example and domestic use cases are similar in that vehicles generally wouldn't have been run flat, and off-peak (load not cost) electricity could have been used for charging, again allowing generators to run at optimum efficiency. Most users in the the domestic case wouldn't need their vehicle until the morning, so could be encouraged to avoid charging at peak demand times by a smart charger which only gives peak output at a lower price when network demand is low via a signal from the grid.
The MOD used to use fleets of electric trucks for on site tasks back in the 1980s. I drove them on a daily basis for about three years and don't ever recall ever having to stop using one due to a flat battery.