This is funny to me cause I came from different background where parking on sidewalk or partially on sidewalk is very common, and there are no cut-outs in the curb. I think your POV is very American, and that is fine. Here are some examples of parking signs, in Poland you will get a ticket for example if you do not park diagonally with at least one tire over the curb when there is a parking sign indicating you must park like so even if your car is a supermini that would fit lengthwise and you wish to save your tire.
I've noticed when that is the case in Europe, the curbs are low and rounded, so it isn't hard too drive over them slowly. When they are high and square like in CA, it wouldn't be easy at all to get on the sidewalk (even if the fascist parking dictatorship were to allow it).
http://jamron.org/2013/05/13/polish-parking-signs/
http://www.gettingaroundgermany.info/zeichen2.shtml