Perhaps a calm and reasoned thought process that you can effectively put into words.
Sorry but the DSM-5 disagrees. Violating social norms is a sign of a anti-social abnormal behavior. In lay terms, a mental illness. One either sees and ignores social norms, or is oblivious. Many examples have been given in this thread. And we could conjure endless examples of the violation of social norms, small and large.
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ttps://www.theravive.com/therapedia/antisocial-personality-disorder-dsm--5-301.7-(f60.2)
"DSM-5 Category: Personality Disorders: Introduction
APD (Antisocial Personality Disorder) is a DSM-5 (Diagnostic and Statistical Manual of Mental Disorders, fifth edition),
diagnosis assigned to individuals who habitually and pervasively disregard or violate the rights and considerations of others without remorse. People with Antisocial Personality Disorder may be habitual criminals, or engage in behavior which would be grounds for criminal arrest and prosecution, or they may engage in behaviors which skirt the edges of the law, or
manipulate and hurt others in non-criminal ways which are widely regarded as unethical, immoral, irresponsible, or in
violation of social norms and expectations. Those with APD often possess an impaired moral conscience and
make decisions driven purely by their own desires without considering the needs or negative effects of their actions on others. Impulsive and criminal behavior is common. The terms psychopathy or sociopathy are also used, in some contexts synonymously, in others, sociopath is differentiated from a psychopath, in that a sociopathy is rooted in environmental causes, while psychopathy is genetically based."
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This parking situation is common. It's a sign of an oblivious thoughtless person, violating a clear social norm, and a sign of a mental illness. It's rather insignificant but it is a sign and in the aggregate it is problematic. It could be passive-aggressive, or narcisstic, or etc. etc. etc.
As far as a suggestion I am unable to put a calm and reasoned thought process into words, it again seems the professional on mental health disagree with you. Suggest your read into the DSM-5. It seems you could benefit for a greater understanding of this topic.
ETA: And FYI, I said twice that I would leave a note on the other persons' window. I don't know what other clear calm concise response I am required to provide here when someone violates social norms.