It's snowed in Boston every year since....well, since there's been a Boston. It's pretty-much universally accepted that if someone shovels out their parking space and puts their lawn chair/treadmill/toilet
there, that's THEIR space. You don't touch their stuff and you find your own parking spot. To do otherwise would risk you getting your tires slashed or a sawhorse thrown through your windshield.
Also, everybody pretty-much accepts that when shoveling out their driveway/parking spot/sidewalk, that you don't just throw the snow back into the street - the plows come by and they don't care.
The plows' primary concern is to clear the roads quickly. They will plow as close to the curb or your car as they can to make as much lane space available. If they end up putting 6" of snow back in front of
your cleared driveway -that's unavoidable collateral damage. They may even laugh about it slightly, just to get through their all-nighter... It's a lonely road they drive....and they drive it alone.