Because for the half of people that take longer trips some might consider bikes unsuitable.
And for the half that does take short trips I doubt they would care or even consider it, just like you.
But I guess that's enough offtopic for this thread.
So if you want to take the car out for a 2km trip go for it, as for me 8'll just walk it, I don't mind a bit of rain or snow as I specifically chose a city that is walkable so I got all I need in 30 mins walking distance or bus ride. I don't even need a car inside the city unless grabbing something heavier from the supply store, but even for that I can go see the item in the store and they will deliver it. Definetly not a daily thing tho