Practicality. They'd be fine for leisure, but not for travel to work if you live outside of Exeter and maybe some other big cities. The population is much more spread out than in larger urban areas. Most people live in smallish towns and villages and commute to work in urban centers (public transport is not good). Either that or they're agricultural workers who need cargo capacity and for whom ebikes would be useless. Also useless for famliles with children who go to school in another town or village. Plus, totally useless in the winter—the winter roads around here and Cornwall are bad enough when you have an SUV.