I can just imagine getting home from work, plugging in, sitting down to dinner and the phone rings. Some sort of emergency (child needs urgent picking up/family member rushed to hospital/any of many other scenarios, except you go to the car to find the charger said no, and it's not even started charging yet, let alone tricked some in over the last hour or two. I'll bet most people have had those sort of "I need the car NOW" situations over the years, especially if you have/had teenage kids or very elderly parents/grandparents.
Yes, I had a situation like this on Saturday. I want to jump into my petrol/hybrid car but I couldn't because I had drank half a bottle of wine. So I got a neighbour to drive.