Fwiw a relevant general concept is that of stable vs. unstable equilibria. In a stable equilibrium, small deviations will tend to correct back to the equilibriu

Fwiw a relevant general concept is that of stable vs. unstable equilibria. In a stable equilibrium, small deviations will tend to correct back to the equilibrium, while in an unstable one, small deviations get magnified and the system drifts away from it (absent active intervention). Given some assumptions, such as those implemented by this simulation, evenly spaced buses represent an unstable equilibrium, since a bus slightly early or late will cause an asymmetry in passenger load that pushes things further in the "wrong" direction.