“There is a car inside
Do not park in front of the door”
When a claim is made on a space, how does the nature of that claim influence how it is heeded? In different contexts, a message being “official” influences how/whether it is heeded in different ways. Here, the lack of an official “No Parking” sign (in a place where the inadequate number of traffic police are often stretched beyond their limits in terms of enforcement capabilities (or are “lazy”/underpaid)) might be perceived as carrying even more “weight” than if there were one. That this warning is handwritten (hand-sprayed?) implies that the person in whose interest it is that you not park there is likely a resident nearby, and that they may summon private means of “enforcement” of their rule. For your context, consider how people regard official warnings vis a vis unofficial ones.
Consider also to what extent phrasing matters. The faded message this gradually decomposing bench once held: “[there are] vehicles entering [and] exiting” – the message left up to interpretation of the driver. The replacement of subtle courtesy with firm visibility, the implied increase in seriousness. What surrounding environmental indicators do to bolster or undermine the implied seriousness of this “law”.