why some cars can't park within its parking space?

parking spaces are usually very generous. cars as big as toyota land cruiser still have a lot of room to move. yet from time to time we see cars parked like this. sometimes small ones too! like what you see in the pic.

it has happened that we had trouble putting our shoppings into the car boot because the gap between our car the the car behind us was only 1mm.

the car in the pic wasn't the car that tried to kiss our car's ass. i just walked passed this car and felt like snapping it.