Edward Rutledge makes this clear to Jefferson and the North when they support an anti-slavery clause to the Declaration of Independence. First of all, Jefferson was also a slaveowner* and despite his promise to free them, the historical Jefferson later decided slavery wasn't so bad after all and only freed a tiny amount and second, most slave ships were captained by New Englanders. Rutledge describes exactly how the Triangle Trade moves in "Molasses to Rum" and then acts out a slave auction.
In a more positive example, John Adams and the chief opponent of independence, John Dickinson. After spending the whole play fighting Adams and seemingly concerned more with material and financial reasons not to rebel, Dickinson finally stands alone against independence. He refuses to sign the Declaration out of conscience because he genuinely thinks it's the wrong path for the country, but because he wants to protect America even in a war that seems hopeless, he leaves Congress and joins the Army. (This is sort of how it actually happened.)
The interactive murder mystery "Killing Mr. Withers" has the villain singing to the Savings and Loan mogul he's trying to murder that they are really not so different from each other. Both of them make a living by ruining other people.
Rock: "Your jig-dancing days are over, little man." Adolph: "But vy? Vy?!" Rock: "In its greed and lust for power, Germany has tried to take over an entire continent." Eva: "But isn't zat vut ze US did in Norze America?" Rock: "Wash your mouth with soap, little lady! Why, the US stopped land-grabbing over forty years ago. And there's a big difference between your land-grabbing and ours." Adolph: "Vut's zat?" Rock: "We succeeded. Besides, we didn't try to wipe out an entire race of people!" Eva: "Vut about ze Indians?" Rock: "Well, we don't lock people away in concentration camps." Eva: "Vut about ze Japanese-Americans on ze Vest Coast?"
In the musical Violet, both Violet and Flick have experienced being judged by their appearance.
In Romeo and Juliet, the very first line establishes that the play is about "two households, both alike in dignity," and pretty much every comparison between the Capulet and Montague families points out that they have much more in common than not.