If I understand correctly, the old streetcar companies weren’t “privatized” (i.e. government-owned assets that were sold off); they were for-profit companies to begin with.
Aside from that quibble, it was true, but then the “willfully left to rot” part kicked in and those transit subsidiaries went bankrupt and ceased to exist. Any rail transit that exists today is either a system that got saved from GM’s plot by being bought by the government (e.g. New York’s subway system), or a government-run system founded more recently (e.g. Washington DC’s subway system).