In Coriolanus, Shakespeare tells us over and over again that if you want to get elected to public office, you've got to have serious acting chops—because winning over voters involves a lot of lying and pretending. In fact, this play shows us that running a political campaign is a lot like producing a stage play. Coriolanus' political advisors come off as nothing more than stage directors trying to guide an actor's speeches and actions. When Coriolanus campaigns for votes, we get the sense that winning over voters is more like winning over a tough theater crowd than anything else.
In Shakespeare's day, actors couldn't actually become politicians. (There were some social class issues involved.) But we get the feeling he wouldn't have been surprised by list.
If politicians are like actors in this play, then Volumnia is the ultimate "stage mom" who spends all her time trying to manage and direct her son's career.
The plebeian voters behave a lot like a fickle theater audience. When Coriolanus appears before them to beg for their votes, they want to be entertained and demand a good performance from their candidate. By comparing them to a theater audience, Shakespeare suggests that they don't deserve the vote.