John Oliver explained public financing of privately owned sports stadiums Sunday on HBO’s Last Week Tonight. It’s a story of teams that decline to open up their books, of fans terrified lest their hometown team follow through on threats to move to Los Angeles, of terminally ill local kids no longer getting visits from big-hearted team members, anxious exotic fish, holograph replay machines, in-stadium swimming pools and a pitch for a new reality series called Ryan Seacrest’s Billion Dollar Dump.