They don't make steel , by and large. Doctors only don' t usually do much more than the speciality of medicine. Physics profs teach physics mainly. Autoworkers make one part of the car . Maybe I am just being dense.
Socialism has socialist or social ownership of the basic means of production.
Capitalism has social production and private appropriation. Socialism has social production and social appropriation. When we say expropriate the expropriators, we mean the people who actually do the work take over ownership of the means of production and own them collectively. The feudal lords and church enforced their private property through tribute and tithes on the working classes.