>Since when is that the definition?
That's the Marxist definition of the Working Class[0], although nowadays some Marxists would programmers, lawyers etc. "Professional Managerial Class" to distinguish them from the workerist idea of the Working Class.
Marx was writing in the very specific context of then-emerging industrial factory production. In Marx's dichotomy, there's workers and those that "own the means of production." That dichotomy makes no sense as applied to what we would call today knowledge workers, and it's probably a misreading of Marx to apply his terminology to them.
In Marx's dichotomy, ownership of the means of production is critical because workers are utterly dependent on that capital to be able to produce anything. That's not true of knowledge workers. A programmer, like a doctor or a lawyer, isn't dependent on a capital owner to produce the thing they sell.
In Marx's dichotomy, ownership of the means of production is critical because workers are utterly dependent on that capital to be able to produce anything. That's not true of knowledge workers. A programmer, like a doctor or a lawyer, isn't dependent on a capital owner to produce the thing they sell.