Note that bunching isn't actually the problem—in fact, bus runs are frequently planned in bunches, with two shorter busses arriving in series simulating a the arrival of a single double-length bus.

The problem, in practice, is people cramming into the nearly-full first bus of a bunch (and delaying the bus further as people slowly fight their way off and on), with another nearly-empty bus following along with nobody getting on it.

This problem would go away if people could be trained to wait for the second bus in the "bunch", rather than getting on the lead one. But, since that change-of-perspective is unlikely to happen, "two fairly full busses leap-frogging one-another" is actually a good solution. It's load-balancing, basically.