Those car windows represent work and labor on someones part, whether the builder, or someone who traded their labor for those car windows. To destroy those windows is to rob someone of their labor. Anarchists clearly frown on robbery, as it is a form of coercion.
This is not a debate on the flavors of anarchism, but an example illustrating that the gang's desire to smash windows is objectively equal to Ed's desire to leave them intact.
If it makes you feel any better, the gang considers the intact windshields to be the "means of production" through which broken windshields are produced. Because the social class of "car owners" cannot use their ownership of these means of production to exert control over the gang, it is necessary for the gang to take "possession" of the windshields while they put they to the use of being smashed.
You can label the thought processes of the gang whatever you like, I really don't care. Call them "anarcho-capitalists" or call them "crypto-facists". The point is that without some moral absolutes, Ed and the gang are on equal moral ground.
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