The problem is that if indiscriminate parking is permitted for you (even though, unbeknown to the warden, you were remaining in your car) everybody would take advantage of the free-for-all. Car parks are laid out so that everybody using them can get in and out of the spaces without too much trouble. If there is no room in the designated spaces you must find somewhere else. The idea that "There's nowhere for me to park legally so I'll leave my car here" is why so many people receive parking tickets and then moan about it.