I don't put it down to people trying to "make space", more down to incompetence IMO.

At least in the UK cars will generally be parked with the handbrake ("emergency brake" in the US AIUI) engaged, meaning that the back wheels will not move, so "nudging" a car will only damage it - if you are "nudging" hard enough to make the stationary wheels slide along tarmac, then that is quite some considerable force. A "little bump" can be enough to cause some expensive damage on modern cars.

So if you are "nudging" another car, I'd put it down to just being a bit of a crap driver who doesn't know what they're doing as you're basically simply driving into things (deliberately or accidentally)