snow&parking

There's something I've been wondering for a long time. When the ground is white, why do people lose the ability to park?
Why does a parking area of 10 spaces suddenly only fit 8 cars? Why do they have to leave their cars much farther than before the snow? Someone might try to say that it is because you cant see the lines of the space anymore. But what if you couldnt even see them without the snow? Lots of people have to struggle finding a space for their car because of the idiots who have parked before them..