Parking lot painting is multi-purposed
The painting in a parking lot generally speaks volumes to the driver or passenger as they first enter the parking lot. In addition, the first impression that the parking lot painting imprints on the visitor, the parking lot painting also serves other functions for the person driving into the parking lot.
Normally, entrance lines and arrows would indicate to the driver the directions that he or she should follow. Often times parkway entrances are one-way, and the person coming in for the first time may be ignorant of the fact if the arrows were not there to impart some form of instruction. Arrows would also be able to guide the driver out of the parking lot to an exit that he or she may not have been aware of. So while many people do often disregard the writings on the wall so to speak, they do in fact serve a purpose to the driver who may be in unfamiliar territories.
Additionally, the parking lot painting instructs us as to where we are allowed to park and where is off-limits to us. In the grocery parking lot for instance, there would be paintings indication loading bays and no parking zones. Even disability zones are normally painted different to the rest of the parking zones for quick and easy differentiation.