It's all on the battery capacity, even in Europe where shorter distances prevail.
The most popular I can see them being is a worse Oil Crisis of the early 1970s, which skyrockets oil prices in Europe who were dependent on Middle Eastern oil. This spurs electric development, particularly in France with it's plentiful cheaper nuclear energy, with battery development increasing from the 50 miles or so in the 1970s to 150 in the 1990s. By the end of the 20th century, electric cars are the norm in most of Europe, and making significant inroads in to areas of North America; the East Coast, California, Chicago area. Japan and South Korea have also experienced a similar switch to Europe.