(People tend) to find local maxima. They’ll find some way to optimize
for the specific thing you’re paying them, without actually achieving
the thing you really want. (...)
Suppose you decide to pay a bonus to the developer with the fewest
bugs. Now every time a tester tries to report a bug, it becomes a big
argument, and usually the developer convinces the tester that it’s
not really a bug. Or the tester agrees to report the bug “informally”
to the developer before writing it up in the bug tracking system. And
now nobody uses the bug tracking system. The bug count goes way down,
but the number of bugs stays the same.