I'm assuming the marks are put on the tread of the tire and if that's the case then it only reasonable violates your privacy for a short duration. This is akin to being seeing in the local strip club parking lot however far less scandalous.
The fact of the matter is that all cars have a unique identifier clearly visible on at least one outward facing surface. It can just as easily be used by LOE to determine how long you've been parked in a spot with a simple app that snaps a photo and logs GPS coordinates.
The differences being that chalk is temporary and can communicate to interested parties that you've parked recently in local vecinity, where as a license plate requires instance observation to track your movements.