Good question tvjunky. By registering your car - you allow your neighbors to contact you immediately regarding issues with your vehicle. So if you were to mistakenly block a neighbors' driveway - they could CurbTXT you to move your car rather than have you towed.
An "F-bomb laced note" wouldn't allow your neighbor to pull out of their driveway.
Registering for CurbTXT also allows your neighbors let you know if you're about to get ticketed for street cleaning, if you've left your lights on by mistake, if someone's smashed your window, etc.
Hope this clears things up, Andrew at CurbTXT (info@curbtxt.com)