The Etiquette of Street Parking

We know that the vernacular changes from region to region, even within a state. Well, I have recently been privvy to the local mores of a city I frequent.
It has to do with snowfall, the sweat generated from shoveling, street parking and one's right to all the above. If you have spent some time and energy digging your car out with a shovel--made for snow or for the coal-bin--or even a soup spoon, you are in the right to claim that spot until the snow melts. See, if you have an all-weather chair, or that week's trash, you can save your cleared parking spot!
This harkens back, I mused, to those grammar school days when you would get your pal to save you a seat on the bus if he got on before you to claim the coveted very backseat! Or, if you wanted to sit with someone at lunch... But, should I really liken the mindset of this hood to children? Doesn't seem fair, when, afterall, they've managed to get driver's licences and successfully mastered the art of parallel parking... Maybe it's a wise-subcultural practice: if you're working 2-3 jobs, you don't really feel like shoveling ad nauseum for others at the end of a long day...Or, if you're on the dole, you still don't feel like shoveling...
Though I must wonder what it's like at rush hour--returning home and finding a doofus has taken your hard-earned, sweat-dried spot. Does a brawl ensue? If you're Mr. Mancini, do you stand guard all day and shake your stick at the offending motorist?