MarkT:
They are not flimsy copper, they are phosphor bronze, a tough alloy used for hard wearing
electrical parts and springs - here the spring that presses the graphite brushes against
the commutator.
As a kid, I took apart a number of these cheap toy 3-6 volt motors to know that there aren't any "graphite brushes" contacting the commutator; I don't know what the material is (could still be phosphor bronze), but inside the motor, it's basically just a simple strip of metal that contacts the copper commutator, nothing more than that.
You don't start to see graphite or carbon brushes on small motors until you start to spend more than 99 cents per each...