marxists agree that the law is unforced, mainly against the working class and the official statistics are flawed. But they criticise labelling theory for ignoring the structure of capitalism within which law making, enforcement and offending take place. Marxist explanations of crime flow from their analysis of the nature of capitalist society.
Marxism sees capitalist society as divided into the ruling capitalist class, who own the means of production, and the working class, who is labour capitalist exploit for profit.
Marxism is a structural theory: society is a structure who is capitalist economy base determines the superstructure i.e. all other institutions, including the state, the law and criminal justice system. Their function is to serve ruling class interests. For Marxists the structure of capitalism explains crime.