It's the number of hook-ups and the processing time that causes issues. Assuming the 10 miles per minute charging rate, it would take up to a half-hour per car to "fill up". Can you immagine waiting in a gas line where almost every vehicle is taking 30 minutes to fuel? How about when everybody wants to charge in Dillon/Silverthorn after skiing? What happens to your EV when you are stuck on the Eisenhower Tunnel approach in a blizzard with the heat, blower and wipers running constantly with a 30% battery that you should have charged but didn't because 40 other EVs were already in line at the last station?